Across:
1 Corrects (AMENDS) academy (A-) workers (-MEN-) doing a job in the station (Detective Sergeant = -DS) (AMENDS),
4 Good-natured (AMICABLE) friend from Lyon (Lyon/French “friend” = AMI-) is on the line (-CABLE) (AMICABLE),
9 Channel (TRENCH) 10 (10 = T-EN-) covers opening of Reformist (opening of ‘reformist’ =-R-) Church (-CH) (TRENCH),
10 Must (must = STUM-) rearrange (= anagram indicator) half the accommodation (half of ‘B&B’ = -B-) for the French (the = -LES) (STUMBLES) trips (trips/falls = STUMBLES),
12 For balanced characters, on foot of a line (TIGHTROPE) out of The Wire (TIGHTROPE),
13 Laid eyes on without nosey (‘laid eyes on’ without ‘nosey’ = laide = IDEAL) model (IDEAL),
14 Only over 21s allowed (DISCRIMINATE) to tell the difference (DISCRIMINATE),
18 Mishandles situation (DROPS THE BALL) and cuts dance (ball) from schedule (DROPS THE BALL),
21 Off the top of my head (ROOTS), they’re embedded in the plot (ROOTS),
22 Hefty (LARGE) wine (PORT) (LARGE PORT) from Marseilles, for instance (LARGE PORT),
24 Charms (ENCHANTS) engineer (E-) with top-notch (top ‘notch’ = -N-) repeats (-CHANTS) (ENCHANTS),
25 Potential victim (QUARRY) of resistance (-R-) to Russian leader (‘Russian’ leader = -R-) in dock (QUA-Y) (QUARRY),
26 Inform locally (inform = S-ING) about college (-C-) music (-RAP- music) (SCRAPING) – it’s really cutting edge stuff, by the sound of it (SCRAPING),
27 Interfere (MEDDLE) with State’s (states = homophone indicator) gold or silver (gold or silver “medal” = “MEDDLE”).
Down:
1 A (A-) tenor (-T-) gets fair amount of (half of) tune (half of ‘tune’ = -TU-) consumed by current (tide = -TI-DE) (ATTITUDE) feelings (ATTITUDE),
2 Greene is (Greene is = ENERGISE) stupid (= anagram indicator) to get a shot in the arm (ENERGISE),
3 Canal (DUC-T) flowing around area (-A-) (DUCAT) in old capital (old capital/gold coin = DUCAT),
5 Grow up (mature = M- -ATURE) around unstable (= anagram indicator) throne (throne = -OTHER N-) (MOTHER NATURE) with her creative force (MOTHER NATURE),
6 Pledge (COMMIT-) for a swinger (-TEE) (COMMITTEE) from the board (COMMITTEE),
7 Is missing from Bastille (‘is’ missing from ‘Bastille’ = batlle = BALLET) in the flames of Paris, for instance (Boris Asafyev’s ‘The Flames of Paris’ = BALLET),
8 They stand up for the artists (EASELS) in the studio (EASELS),
11 Most of (s) Daisy’s relatives (‘Cosmos’ without ‘s’ = COSMO-) endlessly (e) gracious (‘polite’ without ‘e’ = -POLIT-) to a (-A-) new (-N) (COSMOPOLITAN) international traveller (COSMOPOLITAN),
15 Might have been licked in the past but won’t be licked again (RARE STAMP) – presumably you got that from an old man of letters? (RARE STAMP),
16 Foreign footballers (FA-) devour (devour = -VOURED) training (= anagram indicator) (FAVOURED) – it’s how one did a good turn (FAVOURED),
17 Accommodation (FLAT) by Mediterranean port (TYRE Port in Lebanon) (FLAT TYRE) for those with a car is in need of repair, by the way (FLAT TYRE),
19 Olive and Laurel (types of GREENS) take data from Great Danes (take ‘data’ from ‘Great Danes’ = grenes = GREENS),
20 Agree (CONCUR) to cut corners without rest (‘cut corners’ without ‘rest’ = cucorn = CONCUR),
23 Duck (ELUDE) in the swampy water (mud) heading off (m) (‘mud’ without ‘m’ = -UD-) in flowing (= anagram indicator) Lee (Lee = EL-E) (ELUDE).