For complicated reasons to do with ospreys, I ended up solving this at around 3:30 one morning, so I'm not sure I can comment on how easy or difficult it was! Not too hard, I don't think... 13ac and 33dn may be the least widely-known answers, though 23ac may not have been familiar to people based outside the UK.
As always, * indicates an anagram.
| Across |
| 1 | BOTTLE-GREEN - GREEN after BOTTLE |
| 7 | SKINNY LATTE - SKINNY, + Thrill in LATE |
| 13 | TRISKAIDEKAPHOBIA - (apartheid OK I ask)*, around B + I |
| 14 | BAKED - BAD ('off'), around last letters of 'look fine' |
| 15 | ENROBE - ER around N, + OBE |
| 16 | SHEDLOAD - SHED + LOAD |
| 17 | BOULDER - sounds like 'bolder' |
| 19 | ANGLE IRON - IRON after ANGLE |
| 21 | RE-EDITED - TED (Heath), after REED + I |
| 23 | TWOC - TWO + C |
| 25 | IDEAL - I + DEAL |
| 27 | TEETHE - hidden in guaranTEE THEy'll |
| 28 | SEED POTATO - (too deep as)* around Turnip |
| 30 | NOT AT ALL - A in NOT TALL |
| 31 | PLASTIC SURGERY - PLASTICS + URGE + RY |
| 34 | MARKET RESEARCH - MARK + ETRE + SEARCH |
| 35 | VA-VA-VOOM - VA, twice, + V, + moo (reversed) |
| 38 | GRANADILLA - ILL in GRANADA |
| 40 | POROUS - O in PROUSt |
| 41 | DATED - double definition ('saw' in the sense of 'went out with') |
| 43 | COCK - double definition |
| 44 | ABERDEEN - A, + DEE in BERN |
| 45 | A FORTIORI - (for a riot)* + TripolI |
| 48 | UTENSIL - cUes + (listen)* |
| 49 | SKI-SLOPE - IS LOPE, after first letters of 'six kilometres' |
| 50 | GALOSH - LO in GASH |
| 53 | LOTTO - bLOTTO |
| 54 | NOUGHTS AND CROSSES - SAND + CROSSES, after NOUGHT ('love') |
| 55 | THREE-MASTER - Home in TREE MASTER |
| 56 | SILLY SEASON - 'so sane' could indicate SILLY (here, meaning a jumble of) SEASON |
| Down |
| 1 | BOTHERATION - BOss + THE RATION |
| 2 | TRIER - double indication |
| 3 | LIKABLE - LAB around I K, + last letters of 'total carnage' |
| 4 | GRIM - GRIMe |
| 5 | EVEN-HANDED - EVEN, + AND in HE'D |
| 6 | NEANDERTHAL MAN - (had lantern name)* |
| 7 | SCHOONER - SOONER, round C + H (cold and hot; 'taps') |
| 8 | IN BUD - IN + BUD |
| 9 | NAAN BREAD - AN in NAB, + READ |
| 10 | LABOUR - cryptic indication (men don't give birth, so are never in LABOUR) |
| 11 | TAKE DOWN A PEG OR TWO - double indication |
| 12 | EX-DIRECTORY - DIRE + Council, in EX + TORY |
| 18 | PRATTLER - Pin + RATTLER. Definition is 'One may go on' |
| 20 | GREATER MANCHESTER - TERM, in (earnest charge)* |
| 22 | IBERIA - (Aire + Boat + Idly), reversed |
| 24 | GOURMAND - MAN in GOURD |
| 26 | LUTHERAN - first letters of 'living under threat', + HE RAN |
| 29 | PSYCHOANALYSIS - (physical say son)* |
| 32 | SNAPSHOT - SNAPS + HOT |
| 33 | ASHLAR - ASH + LARch |
| 34 | MAGIC BULLET - MAGIC + BULLET |
| 36 | MIDNIGHT SUN - the letter G (good) is in the middle of NIGHT, hence MIDNIGHT is 'cryptically good'; + SUN |
| 37 | SOLAR PANEL - (a person all)* |
| 39 | IMBALANCE - Incisions + MB + A LANCE |
| 42 | DECIPHER - Hole in (pierced)* |
| 46 | TEA ROSE - or ('gold') reversed, in TEASE |
| 47 | ASHORE - 'a sure'could be pronounced in the same way as ASHORE |
| 49 | SKUNK - double definition |
| 51 | OASIS - hidden in AcapulcO AS I Speak |
| 52 | ICKY - pICKY |