ACROSS
 1. _W_ I'LL = WILL <bequeath>
 4. <sweetheart> DARLING = DARING outside L_
 9. <soldier> PRIVATE = PATE outside R IV
10. UR inside BEAU = BUREAU <office>
11. "MEATIER" = METEOR <space traveller>
12. XP AYE inside TAR = TAXPAYER <government supporter>
13. <expert> TECHNOCRAT = (TRENCH COAT)*
16. <chess piece> ROOK = R OO + K
17. <jail> STIR = T inside SIR
18. + (A POP) L, [-h]ECTIC = APOPLECTIC <furious>
20. ←LATS← WART = STALWART <strong>
22. PILL + AR = PILLAR <support>
24. BORNE O = BORNEO <island>
25. G NO + C C H_ I_ = GNOCCHI <dumplings>
26. <government> REGENCY = RE←A, AGENCY
27. <hookup> LINK = L INK

DOWN
 2. <execution> IMPLEMENTATION = (PLAN ON TIME TIME)*
 3. LO I RE = LOIRE <French river>
 4. <runs> DIARRHOEA = D I ARR HOE + A_
 5. <come back in> RE-ENTER = E inside RENT ER
 6. I NB 0 X = INBOX <pile of papers>
 7. G_ CRITERIA* = GERIATRIC <for the elderly>
 8. <classifying> CATEGORISATION = CAT EG ORATION outside IS
14. <one inflexible> HARDLINER = ←DR← inside INHALER*
15. <comms tech> TELEPHONY = POLYTHENE*
19. <venue for mixed martial arts> OCTAGON = OCT AGO N
21. <included with> AMONG = (.n)AMON G(i.)
23. LOW-CAL - W = LOCAL <pub>