Across:
1 Mysterious (= anagram indicator) cleric (cleric = CIRCLE) from Ring (CIRCLE),
4 Contains (INCLUDES) forged (= anagram indicator) uncle’s ID? (Uncles ID = INCLUDES),
9 Shirt-maker hasn’t got this (‘shirt-maker’ hasn’t got ‘this’ = rmaker = REMARK) to say (REMARK),
10 Reports (WRITINGS) of woman (W-) from Rising (rising = RI-INGS) organising (= anagram indicator) around square (-T- square) (WRITINGS),
12 Soldier (GI-) mixes (= anagram indicator) General (general = -NGER ALE) (GINGER ALE) a non-alcoholic spicy drink (GINGER ALE),
13 Look for damages (-SUE) after (= positional indicator) minor relative (sis) loses the head (s) (‘sis’ without ‘s’ = IS-) (ISSUE) with the heirs (ISSUE),
14 For young horses (MAIDEN), a trip that usually contains a water feature (VOYAGE) (MAIDEN VOYAGE) – first time out one might crack open the champagne (MAIDEN VOYAGE),
18 Contributes to The Gloss (FRENCH POLISH) in Paris (FRENCH) and in Warsaw (POLISH) (FRENCH POLISH),
21 Chaperon drops pen (‘chaperon’ drops ‘pen’ = charo = ROACH) in the fresh water (ROACH),
22 Cabling coming out of Buckingham Palace (‘cabling’ coming out of ‘Buckingham Palace’ = ukhmpaace = KAMPUCHEA) and from old part of Asia (KAMPUCHEA),
24 For either partner (“either or” = OR-) setting up (= reversal indicator) duty roster (rota = -ATOR-) at Number 10 (-IO) (ORATORIO) and providing work for the musicians (ORATORIO),
25 Tie up (ATTACH) that (that = ATT-H) mess (= anagram indicator) overshadowing a (-A-) college (-C-) (ATTACH),
26 There’s no pleasing purist (STICKLER) nun (Sr = S-R) with a frog in her throat (-TICKLE-) (STICKLER),
27 Shooting star (METEOR) in remote (remote = METEOR) adaptation (= anagram indicator).
Down:
1 Queen (CARD), The Clash (GAME) (CARD GAME) or Chicago, in a gambling sense? (Chicago is game of poker = CARD GAME),
2 Sentimental (ROMANTIC) Italian (ROMAN-) jerk (-TIC) (ROMANTIC),
3 Trainee (learner = L-) soldier (sergeant) informally (sarge) loses head (s) (“ sarge” without “s” = -ARGE) (LARGE) with major (LARGE),
5 Place for the young plants (NURSERY) is a feature of Limerick (RHYME) (NURSERY RHYME) round and round the garden (NURSERY RHYME),
6 Dismissing someone (LETTING GO) renting a home (LETTING) in the middle of Mongolia (in the middle of ‘Mongolia’ = GO) (LETTING GO),
7 Is rather sweet during the break (DANISH pastry) describing Hamlet (DANISH),
8 Sympathisers disregard parish (‘sympathisers’ disregard ‘parish’ = symtes = SYSTEM) structure (SYSTEM),
11 Transport (CAR-) French wine (French ‘wine’ = -VIN-) by midnight (mid ‘night’ = -G) and use it to cut (KNIFE) (CARVING KNIFE) what’s for the Sunday dinner (CARVING KNIFE),
15 Delves into the foundations (EARTHWORK) of banking technique (bank of soil = EARTHWORK),
16 Drop a line (FISH) to sweet thing (CAKE) (FISH CAKE) – a dishy type in the seafood restaurant (FISH CAKE),
17 Sharpshooter misses? Oops (‘Sharpshooter’ misses ‘Oops’ = shahter = THRASHER) – he’ll wreck the place! (THRASHER),
19 Companies (TROOPS) serve up (= reversal indicator) small (-S) duck (-O-) in wine (port = TRO-P-) (TROOPS),
20 Turns up (= reversal indicator), one (-I) managed (ran) endless (n) (‘ran’ without ‘n’ = -AR-) overseas players (Football Association = FA = -AF-) and headed scouting (headed ‘scouting’ = S-) (SAFARI) expedition to see The Lions and The Jaguars (SAFARI),
23 Relative (auntie) loses head (a) (‘auntie’ without ‘a’ = UNTIE) with what’s free (UNTIE).