Across:
8 A number of families (HOUSES) in The Dáil and The Senate (HOUSES),
9 Don (Don /Mafia = GANGSTER) strange (strange) dress (= anagram indicator) (strange = GAN-STER) going around Gulf (-G-) (GANGSTER),
10 Covered up (= reverse indicator) by yuppie disease (covered up by ‘yuppiE DISease’ = edis = SIDE) on part of The Square (on part of the square = SIDE),
11 Part of the ship (ENGINE ROOM) and part of the car (ENGINE) and part of one of those in 8 across (part of ‘house’ = ROOM) (ENGINE ROOM),
12 Loud (forte = F-) diamond (-ROCK-) top swaying (top ‘Swaying’ = -S) (FROCKS) in the wardrobe of The Abbey? (FROCKS),
14 Describes one of those in 8 across, possibly (DETACHED ‘house’) as divorced (DETACHED),
15 Has a job in government accommodating (HOUSING MINISTER) and sheltering (HOUSING) 18 across (‘minister’ = MINISTER) (HOUSING MINISTER),
18 Is responsible for the department (MINISTER) preaching to those in 26 across (MINISTER preaching to ‘church’),
20 Trendy (MOD-) set (set) mysteriously (= anagram indicator) (set = -EST) (MODEST) unlikely to brag (MODEST),
22 A foreign (UN-) vehicle (-CAR-) that’s red (red)? Failing to start (r) (‘red’ without ‘r’ = -ED) with short (m) body (‘form’ without ‘m’ = FOR) (UNCARED FOR) – it’s been neglected! (UNCARED FOR),
24 Phobia (FEAR) of some still-life artists (some ‘still liFE ARtists’ = FEAR),
25 Relative of tea producer (CAMELLIA) has the hump (CAMEL-) with America city (-L-A) over institute (-I-) (CAMELLIA),
26 Faith (CHURCH) in British statesman (Churchill) dismissed in a bad way (ill)? (‘churchill’ without ‘ill’ = CHURCH).
Down:
1 Firm (company = CO-) structure on the shore (-PIER) (COPIER) is the work of the forger (COPIER),
2 Dislikes ditching kids (‘dislikes’ ditching ‘kids’ = iles = ISLE) in Capri, for example (ISLE of Capri),
3 Welcomes (USHERS IN) those putting them in their place (USHERS) up (= reversal indicator) north (NI = IN) (USHERS IN),
4 Georgian abandons Erin (‘Georgian’ ignores ‘Erin’ = goga = AGOG) waiting with bated breath (AGOG),
5 You (U-) find note (music note -N-): “Get Granny, for one (Granny -KNOT) (UNKNOT), to loosen the purse strings?” (UNKNOT),
6 Loses the head (p) with tweet (‘post’ without ‘p’ = OST-) brought up (raised = -RA-ISED) about college (-C-) (OSTRACISED) that’s blacklisted (OSTRACISED),
7 Farm birds (geese = GE-ESE) flying over heads of number of vultures (heads of ‘Number Of Vultures’ = -NOV-) (GENOVESE) produced by Italians? (GENOVESE),
13 Acting group (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 Relation (relation) travelling (= anagram indicator) (relation = ORIENTAL) with Mao, for instance (ORIENTAL),
17 Salad (= anagram indicator) menu (menu = NUME-) that’s spicy (-RACY) (NUMERACY) is essential for those working on their figures (NUMERACY),
19 Three goals (TREBLE) for the sound engineer to turn around (TREBLE button),
21 Look for someone (SEARCH) to reach (reach) out (= anagram indicator) (reach = -EARCH) to after (= position indicator) school (-S) (SEARCH),
23 An alternative to one of those in 8 across (FLAT is an alternative to one of the ‘houses’) covered up by hyperinflation (covered up by ‘hyperinFLATion’ = FLAT),
24 The Clash (FEUD) can be relatively unpleasant? (can be relatively unpleasant = family FEUD).