ACROSS
1. SHH outside ILLEGAL* = SHILLELAGH <club>
6. <to lose one's cool> THAW = "THOR"
9. "SHOO" = CHOUX <grub>
10. (...s)MALL ORCA N(e...) = MALLORCAN <on isle in Med>
12. <regardless> INCONSIDERATE = CONTAINERISED*
14. FIGHTER outside RE = FREIGHTER <cargo ship>
16. ←LET'S← outside A = STEAL <bargain buy>
17. <some more> EXTRA = EX ←ART←
19. <they travel> WAYFARERS = WAY FAR E + R_S
21. SO UTHER + N CROSS = SOUTHERN CROSS <four stars>
24. <endorsing> AFFIRMING = (MAN IF GRIF_)*
25. <suggestions> IDEAS = I'D EA _S
26. <Olympic sport> EPEE = _E_ _PEE_
27. <assembled> AGGREGATED = AG (GAT inside GREED)

DOWN
1. <lay waste to> SACK = STACK - T_
2. <admire> IDOLISE = (I DO) + LIES*
3. (EX-POACHER GIRL)* = LEXICOGRAPHER <meaning-focused role?>
4. <light unit> LUMEN = L + U MEN
5. GALLEY outside I F_ R_ = GALLIFREY <Time Lords' home>
7. (THE RACE)* = HECTARE <tract of land>
8. W AND RESULT* = WANDERLUST <urge to roam>
11. <upstaging> OVERSHADOWING = OVERS HAD O WIN G
13. AFTERS HAVE = AFTERSHAVE <you get it on your face>
15. <frustrating> THWARTING = THING outside (W + ART)
18. <high-end sweet> TRUFFLE = (FLUTE + F_R)*
20. <most painless> EASIEST = ⭯SIESTA⭯ after E
22. C I ←RAG← = CIGAR <cheroot>
23. <exploited> USED = (...o)USE D(i...)