Across:
1 Tough old bird in hot water (chicken / BOILER only suitable for boiling), as is accountable for the housewarming (BOILER),
4 Raising someone else’s issue (raising someone else’s issue/child is ADOPTION) leads to Bill (AD-) on right to choose (-OPTION) (ADOPTION),
9 Realise (ATTAIN) a (A-) temperature (-T-) ain’t (aint = -TAIN) problematic (= anagram indicator) (ATTAIN),
10 It’s used for transporting (CAR-) the (-TH-E) precious stuff (silver = -AG-) inside (CARTHAGE) Dido’s old place (CARTHAGE was founded by Queen Dido),
12 A really small amount (SCINTILLA) of lilac isn’t (lilac isn’t = SCINTILLA) problematic (= anagram indicator),
13 Portly type (OBESE) honours royal subject (OBE-) at point-to-point (south + east = S+E = -SE) (OBESE),
14 Accountant (CA-) to take advantage of (-USE) minor celebrity (CELEB-) going on about (-RE) (CAUSE CELEBRE) controversial Big Issue (controversial big issue = CAUSE CELEBRE),
18 They’re likely to go off on one (COMBUSTIBLES), having a fiery disposition (COMBUSTIBLE-) on bender (-S bend) (COMBUSTIBLES),
21 China (plate) dismisses the last (e) (‘plate’ without ‘e’ = PLAT-) old (-O) (PLATO), old philosopher (PLATO),
22 Chewed (= anagram indicator) a bad olive (a bad olive = AVOIDABLE) – was that preventable? (AVOIDABLE),
24 Made-up (= anagram indicator) tie clip (tie clip = E-PLICIT) containing cross (-X-) (EXPLICIT) – that’s crystal clear (EXPLICIT),
25 Provocations (TAUNTS) from prominent foundation (‘prominent’ foundation = T-) to relatives (-AUNTS) (TAUNTS),
26 Background (HERITAGE) to one (-I-) child’s game (-TAG-) wrapped up in present (HER-E) (HERITAGE),
27 Hand over (PASS ON) dye (“dye” = “die” = PASS ON) reports (= homophone indicator).
Down:
1 Swede (swede = BRASSICA) gives support for females (BRAS-) at small (-S-) women’s institute (Irish Countrywomen’s Association = -ICA) (BRASSICA),
2 Popular (IN-) soldier (GI = -IG-) set up (= reversal indicator) in bona fide (true = -TR-UE) (INTRIGUE) conspiracy (INTRIGUE),
3 One of The Doors (EXI-T) admits singing the lead (‘singing’ the lead = -S-) (EXIST) – it has something to do with Staying Alive (EXIST),
5 As a reward after working all my life (DRAW A PENSION), tell French architect to sketch a small hotel (“draw a pension/small hotel” = DRAW A PENSION)
6 Serve coffee, for instance (-POUR-), after (= positional indicator) drugs (POT-) fix (rig) briefly (g) (‘rig’ without ‘g’ = -RI) (POTPOURRI), as it changes the smell in the house (POTPOURRI),
7 Drawings (IMAGES) upset (= reversal indicator) great amount of heads (‘great amount’ of heads = GA = -AG-) in house (semi = IM-ES) (IMAGES),
8 Selection drops lot (‘selection’ drops ‘lot’ = seecin = NIECES) of family members (NIECES),
11 Comprehensive (ALL-EMBRACING) covers everything on the curriculum perhaps (ALL-EMBRACING),
15 Worried about the environment (ECOLOGIST), boxer (dog) loses head (d) (‘dog’ without ‘d’ = -OG-) consumed by dangerous bacteria (e coli = ECOL-I-) on street (-ST) (ECOLOGIST),
16 Bold (bold = OLD B-) criminal (= anagram indicator) individuals (-ONES) (OLD BONES) scrutinised by forensic anthropologist (OLD BONES),
17 She ruins (she ruins = USHERS IN) smashing (= anagram indicator) welcomes (USHERS IN),
19 Address (SPEECH) most of the drugs (most of the ‘speed’ = SPEE-) coming from Switzerland (-CH) (SPEECH),
20 Came (CAM-E-) across Park (-P-) and Ride initially (‘ride’ initially = -R) (CAMPER) looking for the pitch (CAMPER),
23 Headmaster releases sheet (‘headmaster’ releases ‘sheet’ = admar = DRAMA) for the players (DRAMA).