ACROSS
1. PROS + THE SIS = PROSTHESIS <auxiliary member>
7/26. CON outside L DOPE = COLD OPEN <scenes before all else?>
9. <incompetent people> SCREW-UPS = CREW inside SUPS
10. <most wintry> ICIEST = CITIES*
11. (STORAGE SPACE)* = SCAPEGOATERS <chargers>
13. FE DORA = FEDORA <headgear>
15. STEP ON IT = (SET POINT)*
17. <U-turn> REVERSAL = RE VEAL outside R_ S_
19. <sweet> TOFFEE = _EE_ after TOFF
20. BE LEAGUE RING = BELEAGUERING <annoying>
24. (PR outside A KO) A = PAKORA <Indian dish>
25. HE ADS HOT = HEADSHOT <portrait>
27. *£*(READS)*£* = ADDRESSEES <names on letters>

DOWN
2. RI CO "SHADE" = RICOCHETED <bounced back>
3. <make tea> STEEP <overly expensive>
4. H LASS outside O URG_ = HOURGLASS <slim-waisted figure?>
5. <ostentatiously proceeds> SASHAYS = "SACHETS"
6. _SK_ + IVE = SKIVE <bunk>
7. LOWRISE* inside CF = CRIES WOLF <alarms pointlessly>
8/23. <bitter end> LAST GASP = (ATLAS + GPS)*
12. <classify> PIGEONHOLE = G_ inside OENOPHILE*
14. (WOOL* outside VERB) N = OVERBLOWN <excessive>
16. <followers> ENTOURAGE = ENCOURAGE, T←C
18. <hated> LOATHED = LOAD outside THE
21. ←MALL← A = LLAMA <wool supplier>
22. R + USES = RUSES <gambits>