Jumbo 1321

This took me 55 minutes all told so that would put it on the slightly tricky side of average and I thought there was some extremely good stuff here, including plenty of very neat wordplay and a decent smattering of hard-to-spot definitions.

Clues are in blue with definitions underlined and, hopefully, the explanations all making sense.  I'm going to be in France for the day when this blog will, with any luck, magically appear on your screens so any queries are unlikely to be dealt with for a while.

First in was MACRO, last was ARMPITS

Across
1	Flagon of beer as conveyed by Spooner to dance (9)
	JITTERBUG - Spoonerism of bitter jug
6	Novelist’s oddly set view lacks moral, ultimately (9-4)
	SACKVILLE-WEST - anagram of set view lacks and the last letter of moral. Vita Sackville-West was a successful novelist, poet and journalist, as well as a prolific letter writer, diarist and garden designer.  The lazy get.
13	Lens for camera cases returned (5)
	MACRO - Reverse hidden in fOR CAMera.  Nice clue with "cases returned" being the very neat combination of reversal and containment indicators, camera cases needing to be separated and the wordplay elements fitting seamlessly with the definition in the surface reading.  A macro lens enables you to take extreme close-up photos of things like insects, flowers and navel fluff.
14	Early Christians sneakily ensnare a leader of Zionism (9)
	NAZARENES - (ensnare a zionsim)*.  I'm not sure if "sneakily" works perfectly as an anagram indicator but it didn't hold me up.
15	Boy fronting pupils’ moving proposition (7)
	THEOREM - THEO R.E.M.
16	Endure a bitter little general harbouring fancy project, obviously (5,3,4,1,4,5)
	STICK OUT LIKE A SORE THUMB - STICK OUT for endure with a cryptic nod to "little" General Tom Thumb with a cob on.
18	Boy soon getting around large resistance (8)
	ALGERNON - ANON around LGE (short for large) R[esistance]
20	Did like eating vegetables, becoming satisfied (8)
	APPEASED - APED (did like as in acted like) around PEAS.  Neat.
21	Pole appearing earlier in Gdansk (5)
	NORTH - This took me a while to fathom.  Of the two poles appearing in the word GDANSK the N comes before the S.
23	Note first of series of books portraying Italian town (6)
	TIVOLI - TI VOL[ume] I
24	Host clutching very large and fine decoration (6)
	MOSAIC - M.C. around OS AI
25	Plant arrived at by pilot carpeted with gold (3,6)
	FLY ORCHID - FLY (to pilot) then CHID with OR
28	Some biscuits and bread carried out by one on plane (6,4)
	BARREL ROLL - I'm not a fan of clues like this where a verbal definition is deemed sufficient for a nounal answer.  IMHO this one is lacking "this could be" or "something" or summat along those lines.
29	Party to open pub with ball... (2,2)
	IN ON - O (ball-shaped letter) inside (opening) INN.  Nicely concealed definition.
30	...Ring to cancel our party (7)
	ANNULUS - ANNUL US
32	Depressions drastically increase militancy of mining unions? (7)
	ARMPITS - ARM PITS
34	Change from upright character into criminal (4)
	COIN - I in CON
35	Periodical not available to convey a historic document (5,5)
	MAGNA CARTA - MAG N/A CART A
38	During vacation, lass meeting Irish Americans in neighbourhood? (9)
	HOMEGIRLS - MEG IR[ish] in HOLS. An informal US (and South African term) for a young female acquaintance from one's own town or neighbourhood, or from the same social background.
39	What widow would give not to end a recluse (6)
	HERMIT - HER MITe
40	Bring up something one’s pinned to one’s ear (6)
	BROACH - Sounds like BROOCH (any dissenters?)
43	Had perished at sea, in doctor’s absence (5)
	OWNED - drOWNED
45	Boy needs mum: is that unusual? (8)
	MATTHIAS - MA + (istaht)*
47	Impracticable cunning failed to get a hearing (4-4)
	WILD-EYED - Sounds like WILE DIED
49	And so send them to sleep in just a pyjama jacket? (4,3,5,3,7)
	BORE THE PANTS OFF SOMEONE - CD
52	Popular novelist doesn’t stop interfering with books? (7)
	COOKSON - COOKS ON
53	I run in, this time (6,3)
	COMMON ERA - ONE R[un] in COMMA.  Sneaky.
54	Extract from a little white lie (5)
	WREST - W[hite] REST
55	Mir apparently going around the earth, for example (7,6)
	PRIMARY PLANET - (mir apparently)*
56	One traducing Solicitor at Law: and before king! (9)
	SLANDERER - SL AND ERE R.  Of the myriad things that SL can apparently stand for (e.g. Steam Locomotive, Secret Lover and Space Laser) Solicitor at Law is one.

Down
1	Politician and celebrity involved in project get going (4,5)
	JUMP START - M.P. STAR in JUT
2	Reprimand, not very loud, and very short, for idling (7,4)
	TICKING OVER - TICKING OFF with VERy replacing FF
3	Tips for office job: do no donkey-work and no paperwork! (5)
	EBOOK - An ebook would be a no paper work.  Geddit?
4	Bedroom at first holding advantage over study (4,2,2)
	BONE UP ON - B(edroom) ONE UP ON
5	Scoff when crossword’s abandoned quietly for good (6)
	GUZZLE - G replacing P in PUZZLE
6	Format for golf talk arranged with pro? Yes (10)
	STROKEPLAY - (talk pro yes)*
7	Getting fit again, do trail across glen (12)
	CONVALESCENT - CON SCENT around VALE
8	Thick aristocrat trading books for seconds (7)
	VISCOUS -S[econds] replacing N[ew] T[estament] in VISCOUNT
9	Coffee time’s about right? Isn’t for a Mormon (6-3,5)
	LATTER-DAY SAINT - LATTE DAY'S around R then AIN'T.
10	Oriental drama used to be turned to Victorian satire (7)
	EREWHON - reversal of NOH WERE.  A novel by Samuel Butler.
11	State official left inside hears alarm going off (4,7)
	EARL MARSHAL - L in (hears alarm)*
12	Nurse could take this work through agency? (4)
	TEMP - If you're a temporary worker you're said to be temping and a nurse can take your TEMP(erature), ideally under the tongue or in the armpit...
17	Country no longer could come to hero’s aid (8)
	RHODESIA - A sort of reverse anagram, involving the letters of HERO's AID
19	Discharging energy again going through stocks (9)
	RELIEVING - E[nergy] inside (stocked by) RE-LIVING (again going through)
22	Yanks holding Republican line in mess (8)
	HORLICKS - R[epublican] L[ine] in HOICKS.  This might baffle overseas solvers.  Horlicks is a brand of malt-based bed-time hot drink powder and is used in expressions like "he made a right horlicks of that".  I suspect it's a euphemism for a certian B- word.
25	Lover one day turned up with a Disney film (8)
	FANTASIA - FAN then I SAT[urday] reversed and A
26	Bothered following leads that brave folk wouldn’t? (3,6)
	RUN SCARED - CARED after LEADS
27	Translated first, sign small, compact novel (8,6)
	TRISTRAM SHANDY - TR[anslated] 1ST RAM S[mall] HANDY.  Laurence Sterne novel about the inventor of lager and lime.
28	Ace hobby, training to become lifeguard (8)
	BEACHBOY - (ace hobby)*
31	Appropriate to give maiden an indispensable partner (5-4,3)
	RIGHT-HAND MAN - RIGHT HAND M[aiden] AN
33	Reminder of passing minutes — no more time, sadly (7,4)
	MEMENTO MORI - M[inutes] + (no more time)*
36	Draw in study period that’s not specially tailored (5-2-4)
	READY-TO-WEAR - TOW in READ YEAR
37	My Greek food company not touching alcohol (5,5)
	GREAT SCOTT - GR[eek] EATS CO[mpany] TT.  One of the well-disguised defs I referred to in my preamble.
41	Swindled punter ought to (3,6)
	HAD BETTER - er, HAD + BETTER
42	Family’s experiences near a city in Africa (8)
	KINSHASA - KIN'S HAS A
44	In the main, SAE speeds up packages (4-3)
	DEEP-SEA - reverse hidden, beautifully woven into a neat surface reading.
46	Variable illustration featuring in short story classic (7)
	TYPICAL - Y PIC[ture] in TALe
48	Pudding is where you’ll get tea, in a manner of speaking (6)
	AFTERS - in a manner of speaking tea = T which comes AFTER S in th'alphabet
50	Laconic admission from groom sounded pitiful (5)
	MEWED - You Tarzan, ME WED. "Mr Burtenshaw?". "Me doctor?". "No, me doctor, you Mr. Burtenshaw".
51	Drink bottles beginning to contaminate fish (4)
	SCUP - C(ontaminate) in SUP.  I don't think I've ever seen scup on the menu at the Wetherby Whaler.