Across:
8 Assembled by 15 across (HOUSES assembled by ‘housing minister’) in The Dáil and The Senate (HOUSES),
9 Is responsible for the department (MINISTER) closing 15 across (‘housing minister’ = MINISTER),
10 Damaged (= anagram indicator) skin (skin = INKS) suitable for tattoos? (INKS),
11 Is in The Transporter (ENGINE), Othello (Moor = ROOM), Revolution (= reversal indicator) (ENGINE ROOM) and is the beating heart of Titanic, for example (ENGINE ROOM),
12 Has an influence on the count (ABACUS), as what’s monitored is not in sodium carbonate (‘monitored’ is not in ‘sodium carbonate’ = sucaba = ABACUS),
14 Unattached (DETACHED) to one of those in 8 across, for example (one of ‘houses’ = DETACHED house),
15 Person responsible for ground-breaking development in the cabinet (HOUSING MINISTER) providing shelter (HOUSING) for religious speaker (MINISTER) (HOUSING MINISTER),
18 Initially slimmer (initially ‘slimmer’ = S-) and fitter (-TRIMMER) (STRIMMER) from cutting down on the grass (STRIMMER),
20 Some à la mode structure (some ‘à la mode structure’ = MODEST) that’s not pretentious (MODEST),
22 Makes a really big deal (MEGA-MERGER) of Margaret (MEG-) and Albert (-A-) getting married (-M-) by church official (verger) losing the head (v) (‘verger’ without ‘v’ = -ERGER) (MEGA-MERGER),
24 It’s even (FLAT) covered up by hyperinflation (covered up by ‘hyperinflation’ = FLAT),
25 Double agents dismiss lead (‘double agents’ dismiss ‘lead’ = oubgents = GONE BUST) that could explain how one lost everything in the business (GONE BUST),
26 Abbey (CHURCH) in old city (-UR-) surrounded by couple of religious institutions (CH-CH) (CHURCH).
Down:
1 Rub shoulders (HOBNOB), back (= reversal indicator) and top of the nape (top of the ‘nape’ = -N-) digging into Robert? (Bob = -B-OB) That explains it! (Oh = HO-) (HOBNOB),
2 Pops the question (ASKS) to Ring’s assistant on the books (Ring’s ‘assistant on the books’ = ASKS),
3 She ruins (she ruins = USHERS IN) smashing (= anagram indicator) welcomes (USHERS IN),
4 Groomsman dumps Norma (‘groomsman’ dumps ‘Norma’ = goms = SMOG) – it creates a bad atmosphere (SMOG),
5 Organisation (UN-) gets granny, for one (Granny -KNOT) (UNKNOT), to relax in muscular way (UNKNOT),
6 Loses the head (p) with tweet (‘post’ without ‘p’ = OST-) uploaded (raised = -RA-ISED) about college (-C-) (OSTRACISED) that’s blacklisted (OSTRACISED),
7 Even goes (even goes = GENOVESE) off (= anagram indicator) one of those in northern Italy (GENOVESE or Genoese),
13 The players (CAST-) from one (-I-) theatre (-GATE- Theatre) got director (-D) (CASTIGATED) to read The Riot Act (reprimand / CASTIGATED),
14 Show reluctance (DEMUR) to express doubts (DEMUR),
16 Where one finishes one sentence (ON THE DOT) exactly (ON THE DOT),
17 Salad (= anagram indicator) menu (menu = NUME-) that’s spicy (-RACY) (NUMERACY) is essential for those working on their figures (NUMERACY),
19 Submissive type (meek) briefly (k) (‘meek’ without ‘k’ = MEE-) finds uplifting (= reversal indicator) place (put = -T UP) (MEET UP) for get-together (MEET UP),
21 Look for someone (SEARCH) to reach (reach = -EARCH) out (= anagram indicator) to after (= position indicator) school (-S) (SEARCH),
23 Providing a terrible sample (‘providing a terrible’ sample = GATE) at the airport (GATE),
24 Blots out self-doubt (‘blots’ out ‘self-doubt’ = efdu = FEUD) and animosity (FEUD).