Across:
1 Votes (votes) lost (= anagram indicator) (votes = SOV-ET) around island (-I-) (SOVIET) by old council (old local, district or national council = SOVIET),
4 Most of (e) the dish (‘platE’ without ‘e’ = (PLAT -) on paper (-FORM) (PLATFORM) is a level above the rest (PLATFORM),
9 Meeting leaders perhaps (CHAIRS lead meetings) misrepresented (= anagram indicator) as rich (as rich = CHAIRS),
10 Got it (OBTAINED) from group (mob) losing the head (m) (‘Mob’ without ‘m’ = OB-) with politician (TD = -T-D) over the Celtic goddess from summer long ago (Áine = Celtic goddess of summer, wealth and sovereignty = -AINE-) (OBTAINED),
12 Nothing (NAUGHT-) from Ireland (.ie = -IE-) at the foundation in particular (foundation in ‘particulaR’ = -R) (NAUGHTIER) is more mischievous (NAUGHTIER),
13 Posts (SENDS) lie out of idleness (‘lie’ out of ‘idleness’ = dness = SENDS),
14 Took a seat (SAT-) from one (-I-) small (-S-) dissenting clique (-FACTION) (SATISFACTION) – that’s fulfilment! (SATISFACTION),
18 Presumably, The Weather Girls recorded them (TEMPERATURES) with The Three Degrees and others (TEMPERATURES)
21 Put a line through (ERASE) some disclaimer as expected (some ‘disclaimER AS Expected’ = ERASE),
22 It’s not different (IDENTICAL) to tritium (-T-) and iodine (-I-) found in Iceland? (Iceland) Wrong! (= anagram indicator) (Iceland = IDEN-CAL) (IDENTICAL),
24 Is shown on television (airs = AIR-S) consuming wine (-PORT-) (AIRPORTS) designed specifically for high-flyers (AIRPORTS),
25 Join the Freedom Fighters? (fight = RESIST) Don’t let that happen! (RESIST),
26 Kitty (POOL-) is on edge (-SIDE) (POOLSIDE) hovering near the water, a popular holiday spot (POOLSIDE),
27 Star (LEGEND), for example (e.g. = -EG-), discovered in advance? (L-END) (LEGEND).
Down:
1 Good health – it's not (SICKNESS is not good health) something you often see in hospital! (SICKNESS),
2 Cuts diva (cuts diva) out (= anagram indicator) (cuts diva = VIADUCTS) of the versions of The Bridge (VIADUCTS),
3 Where to find everyone (EARTH) with heart (heart) problem (= anagram indicator) (heart = EARTH),
5 Party (Labour) dismisses Unionist leader (‘Unionist’ leader = u) (‘Labour’ without ‘u’ = LABOR-), a (-A-) number of overseas politicians (-TORIES) (LABORATORIES) and those employing scientists (LABORATORIES),
6 Tenor (T-) managed (-RAN-) to open spirits (open ‘Spirits’ = -S-) to drink (-PORT) (TRANSPORT) and carry away (TRANSPORT),
7 Possessing (OWNING) hats from Washington (‘hats’ from ‘Washington’ = wingon = OWNING),
8 Humble (MODEST) times – Down not getting win (‘times – Down’ not getting/without ‘win’ = tmesdo = MODEST),
11 Frustrated (DISAPPOINTED) as Old Penny (£SD / old penny = D-) is (-IS-) taken on (-APPOINTED) (DISAPPOINTED),
15 The bare bones (SKELETONS) of what ancient diggers dug up of late (SKELETONS),
16 Custom (PRACTICE) in remarkable (= anagram indicator) Capri, etc. (Capri etc = PRACTICE),
17 It’s hard to find (ISOLATED) one (I-) local criticised harshly (local ‘criticised harshly’ = slated = -S-LATED) over nothing (-O-) (ISOLATED),
19 Father (REV-) and mother (Ma) backed (= reverse indicator) (Ma = -AM-) park (-P) (REVAMP) getting overhaul (REVAMP),
20 Bob (HAIRDO) runs the committee (chair) without leader (c) (‘chair’ without ‘c’ = HAIR-) from party (-DO) (HAIRDO),
23 What’s the subject (THEME) of groan from hatemonger? (‘groan’ from ‘hatemonger’ = hteme = THEME).