Very good workmanlike puzzle. Nothing specially noteworthy, although 18a was nicely disguised (it took some passes before I spotted it). And 22a was well hidden. No I certainly didn't know the Korean money so I had to get 18a first. Just under 6 minutes with a chunk of time spent with the wonton soup in the SW corner. Definitions in blue italic underlined. Answers in bold caps.
Across
1. Duke has possession of hills (5)
DOWNS. D=duke (as often in crosswords), OWNS=has.
4. Rest day brings Southern seaman to city (7)
SABBATH. S plus AB (sailor) plus Bath=city.
8. Informed attitude about drink(7)
SANGRIA. Sang=informed plus AIR reversed (attitude).
9. Take front off roof beam at later time (5)
AFTER. [R]after=roof beam with the front off.
10. Greek character don droned on aboutshrub (12)
RHODODENDRON. Rho=Greek character plus anagram of DON DRONED. I liked the idea of the don droning on. "Rhodo" comes from the Greek "rose" and "dendron" from "tree".
12. Old mathematicianreturning snooker equipment cover (6)
EUCLID. Our other Greek clue. Snooker cue reversed (returning) plus LID=cover.
13. Small and attractive- favourite item Monsiieur's missed (6)
PETITE. PET=favourite plus ITE, "item" minus M[onsieur].
16. Widespread stick fortop officers (7,5)
GENERAL STAFF. Amusing. GENERAL=widespread and STAFF=stick.
18. Add life to routine, English not exaclty working initially (5)
RENEW. No idea why but it took me a long time to see this. First letters (initially) in r[outine] E[nglish] n[ot] e[xactly] w[orking].
20. Messenger in firm, curt ignoring outsiders? That's right (7)
COURIER. CO (company or firm) with [c]ur[t] plus i.e. r[ight].
21. Pit worker welcomes a Republican sailor (7)
MARINER. MINER (pit worker) contains a R[epublican].
22. Movable mechanism from Munich in Germany (5)
HINGE. Contained in [Munic]h in Ge[rmany]. Again I don't know why I didn't spot this much faster but I went looking for the German word for Munich (Munchen). Nice misdirection by the setter.
Down
1. Merit of French verse, translated (7)
DESERVE. DE=of (in French) plus anagram of VERSE (translated).
2. Order new car and old wine for glass worker(6,7)
WINDOW CLEANER. Anagram of NEW CAR OLD WINE (order).
3. Preach of dreadful mores in South East (9)
SERMONISE. Anagram (dreadful) of MORES IN contained in SE.
4. One criticising roof worker (6)
SLATER. Double definition.
5. Stole unfinished vessel (3)
BOA. Boa[t].
6. Aura, iron, that I represented as strict (13)
AUTHORITARIAN. Anagram (represented) of AURA IRON THAT I.
7. Difficult- that endless road (4)
HARD. [T]HA[T] plus RD=road.
11. Drug upset unfashionable, hot US area (4,5)
DEEP SOUTH. SPEED=drug, backwards (upset) plus OUT=unfashionable, plus H[ot].
14. Ensure observance of education extremely supportive of church (7)
ENFORCE. First and last letters of E[DUCATIO]N (extremely) FOR=supportive. CE=church (Church of England).
15. Tripper familiar with Charleston perhaps (6)
DANCER. TRIPPER, as in tripping a measure, and CHARLESTON, as in the energetic1920's dance.
17. Regularly perform in concert (4)
PROM. Every other letter (regularly) in P[E]R[F]O[R]M. Here it's one of the venerable concert series held annually at the Albert Hall in London. In the US it's the dance held at the end of the senior year in high school, which sometimes turns up in these puzzles.
19. GotKorean money (3)
WON. Double definition.
Across
1. Duke has possession of hills (5)
DOWNS. D=duke (as often in crosswords), OWNS=has.
4. Rest day brings Southern seaman to city (7)
SABBATH. S plus AB (sailor) plus Bath=city.
8. Informed attitude about drink(7)
SANGRIA. Sang=informed plus AIR reversed (attitude).
9. Take front off roof beam at later time (5)
AFTER. [R]after=roof beam with the front off.
10. Greek character don droned on aboutshrub (12)
RHODODENDRON. Rho=Greek character plus anagram of DON DRONED. I liked the idea of the don droning on. "Rhodo" comes from the Greek "rose" and "dendron" from "tree".
12. Old mathematicianreturning snooker equipment cover (6)
EUCLID. Our other Greek clue. Snooker cue reversed (returning) plus LID=cover.
13. Small and attractive- favourite item Monsiieur's missed (6)
PETITE. PET=favourite plus ITE, "item" minus M[onsieur].
16. Widespread stick fortop officers (7,5)
GENERAL STAFF. Amusing. GENERAL=widespread and STAFF=stick.
18. Add life to routine, English not exaclty working initially (5)
RENEW. No idea why but it took me a long time to see this. First letters (initially) in r[outine] E[nglish] n[ot] e[xactly] w[orking].
20. Messenger in firm, curt ignoring outsiders? That's right (7)
COURIER. CO (company or firm) with [c]ur[t] plus i.e. r[ight].
21. Pit worker welcomes a Republican sailor (7)
MARINER. MINER (pit worker) contains a R[epublican].
22. Movable mechanism from Munich in Germany (5)
HINGE. Contained in [Munic]h in Ge[rmany]. Again I don't know why I didn't spot this much faster but I went looking for the German word for Munich (Munchen). Nice misdirection by the setter.
Down
1. Merit of French verse, translated (7)
DESERVE. DE=of (in French) plus anagram of VERSE (translated).
2. Order new car and old wine for glass worker(6,7)
WINDOW CLEANER. Anagram of NEW CAR OLD WINE (order).
3. Preach of dreadful mores in South East (9)
SERMONISE. Anagram (dreadful) of MORES IN contained in SE.
4. One criticising roof worker (6)
SLATER. Double definition.
5. Stole unfinished vessel (3)
BOA. Boa[t].
6. Aura, iron, that I represented as strict (13)
AUTHORITARIAN. Anagram (represented) of AURA IRON THAT I.
7. Difficult- that endless road (4)
HARD. [T]HA[T] plus RD=road.
11. Drug upset unfashionable, hot US area (4,5)
DEEP SOUTH. SPEED=drug, backwards (upset) plus OUT=unfashionable, plus H[ot].
14. Ensure observance of education extremely supportive of church (7)
ENFORCE. First and last letters of E[DUCATIO]N (extremely) FOR=supportive. CE=church (Church of England).
15. Tripper familiar with Charleston perhaps (6)
DANCER. TRIPPER, as in tripping a measure, and CHARLESTON, as in the energetic1920's dance.
17. Regularly perform in concert (4)
PROM. Every other letter (regularly) in P[E]R[F]O[R]M. Here it's one of the venerable concert series held annually at the Albert Hall in London. In the US it's the dance held at the end of the senior year in high school, which sometimes turns up in these puzzles.
19. GotKorean money (3)
WON. Double definition.