Across:
8 Rome by (Rome by) train? (= anagram indicator) (Rome by = EMBYRO) That’s in the early stage of development! (EMBYRO),
9 A sincere (a sincere) adaptation (= anagram indicator) (a sincere = INCREASE) of Spiral (Spiral = INCREASE),
10 Manages to leave fun and games (‘manages’ to leave ‘fun and games’ = fund = FUND) to Kitty (kitty/purse = FUND),
11 It’s true (fact = FAC-T-) about leaders in Little Italy (leaders ‘In Little Italy’ = -ILI-) put away (-ATE) (FACILITATE) to make things possible (FACILITATE),
12 Starting from here (starting from ‘Here’ = -H-) in confidence (trust = T-RUST) (THRUST) by barge (barge/push = THRUST),
14 Brood (brood/family = LITTER-) in hospital (-ER) (LITTERER) with one of those spreading rubbish (LITTERER),
15 Give up (THROW IN THE TOWEL) soft furnishing (THROW) popular (IN) with most of them (most of ‘them’ = THE) spread on the beach? (TOWEL) (THROW IN THE TOWEL),
18 To start off (INITIATE), one (I-) fool (-NIT-) got single (-I-) and wolfed it down (-ATE) (INITIATE),
20 Key (music key = G-) admission (-ENTRY) (GENTRY) by those in a class (GENTRY),
22 It’s wrong (X-) for individual (one = -ENO-) going around (= reverse indicator) one = -ENO-) with fear (-PHOBIA) (XENOPHOBIA) or hatred of foreigners (XENOPHOBIA),
24 Beastly type (PUMA) turns (= reversal indicator) up (up = PU-) to graduate (-MA) (PUMA),
25 Cast aspersions on (DENOUNCE) poor student (D-UNCE) over one (one) review (= reversal indicator) (one = -ENO-) (DENOUNCE),
26 Diner (EATERY) from steelyard drops LSD (‘steelyard’ drops ‘LSD’ = teeyar = EATERY).
Down:
1 Stick up (AMBUSH) for Dawn (dawn/morning = AM-) on transport (-BUS-) with hothead (‘Hot’ head = -H) (AMBUSH),
2 Brigades’ dismissed base (‘brigades’ dismissed ‘base’ = rigd = GRID) network (GRID),
3 The Paper covering the match (CONFETTI) is thrown by those United supporters? (CONFETTI),
4 Locked up in Alcatraz in California (locked up in ‘alcatraZ IN California’ = ZINC) for galvanising steel (ZINC),
5 Locates spur, removing a rose (‘locates spur’ removing ‘a rose’ = lctspu = SCULPT) cut from stone, in a way (SCULPT),
6 Take pressure off (SETTLE) one of The Blues (one of the blues = sad = DOWN) (SETTLE DOWN) to kick back? (SETTLE DOWN),
7 Problematic (= anagram indicator) satire (satire = AS IT -RE) about you and I (WE-) (AS IT WERE) in a manner of speaking (AS IT WERE),
13 It’s out of the ordinary (UNORTHODOX) for a foreign (a = UN-) conformist (-ORTHODOX) (UNORTHODOX),
14 Man taken out of terminal (‘man’ taken out of ‘terminal’ = teril = LITRE) has capacity to hold less than two pints (LITRE = 1.75 pints),
16 Longed for (HANKERED for) a herd Ken (a herd Ken) lost (= anagram indicator) (a herd Ken = HANKERED),
17 One of those doing the scoring (ENGRAVER) determines whose name goes on the cup (ENGRAVER),
19 Model (= anagram indicator) hates (hates = ATHE-S) taking in new (-N-) (ATHENS) city in Europe (ATHENS),
21 Shirt-maker hasn’t got this (‘shirt-maker’ hasn’t got ‘this’ = rmaker = REMARK) to declare (REMARK),
23 Raised (BRED) local money (bread) on the radio (= homophone indicator) (‘bread’ = ‘BRED’),
24 Shame (PITY) one of The Stones (PIT-) joins Yes (-Y) (PITY).