Fabulous fun.
Thanks to Goliath for a most enjoyable challenge. This setter can be quite tricksy at times, but I found this very accessible, but still a satisfying solve.

ACROSS
1. Perhaps New Zealander and South American will take hint by the first of October (10)
ANTIPODEAN
ANDEAN (South American) will take TIP (hint) by O[ctober] (first of)
6. Finally cross bench and heave (4)
SPEW
[cros]S (finally) + PEW (bench)
9. Assorted mixture of island folk (2,3,5)
OF ALL KINDS
(ISLAND FOLK)* (*mixture of)
10. Designer uniform clothing could be a snare (4)
DRUM
D[esigne]R U[nifor]M (clothing)
A snare is one type of drum, hence ‘could be’
12. Consequence concerning 10s (12)
REPERCUSSION
RE (concerning) + PERCUSSION (10s, referring to 10 across and note the S for plural)
15. Ghetto in Spain, both short of food (9)
SPAGHETTI
GHETT[o] (short) in SPAI[n] (short), i.e. both short
17. Like gardens to be lopsided (5)
ASKEW
AS (like) + KEW (gardens)
18. Getting into taxi always pivotal (5)
AXIAL
[t]AXI AL[ways] (getting into)
19. Syndicates regularly employed so-and- so to disrupt aortic treatment (9)
CONSORTIA
[s]O-[a]N[d]-S[o] (regularly employed) to disrupt AORTIC* (*treatment)
20. Not far from Mick Jagger’s perhaps extraordinary worth (1,6,5)
A STONE’S THROW
A STONE’S (Mick Jagger’s, perhaps) + WORTH* (*extraordinary)
24. Country’s intelligence captures central laboratory (4)
IRAQ
IQ (intelligence, intelligence quotient) captures [labo]RA[tory] (central)
25. Most important and complete part of Yorkshire (10)
OVERRIDING
OVER (complete) + RIDING (part of Yorkshire)
26. Want to be heard, do some baking! (4)
NEED
“KNEAD” (do some baking, “to be heard”)
27. It’s no problem coming in puffed up and under the influence (10)
HYPNOTISED
(IT’S NO)* (*problem) coming in HYPED (puffed up)
DOWN
1. Excited to enter synagogue (4)
AGOG
2. Wood frames for the artwork (4)
TEAK
T[h]E A[rtwor]K (frames for)
3. Lonely type, he recycled plastic (12)
POLYETHYLENE
(LONELY TYPE HE)* (*recycled)
4. Doctor and author has energy (5)
DRIVE
DR (doctor) and I’VE (author has)
5. Extra cover for Charlie’s habit (9)
ADDICTION
ADDITION (extra) cover for C (Charlie)
7. Each prison disturbed yet particular (10)
PERNICKETY
PER (each) + NICK (prison) + YET* (*disturbed)
8. Ladies curse their garments (10)
WOMENSWEAR
WOMEN (ladies) + SWEAR (curse)
11. Key justifier is one getting out of a bind (12)
ESCAPOLOGIST
ESC (key) + APOLOGIST (justifier)
13. Rise of criminal case circle in American region (10)
ESCALATION
CASE* (*criminal) + O (circle) in LATIN (American region)
14. Publication by creative artist beginning to exasperate judge (10)
MAGISTRATE
MAG (publication) by ARTIST* (*creative) + E[xasperate] (beginning to)
16. Around 55, losing cash yet computer literate (4-5)
TECH-SAVVY
Around V V (5 5), (CASH YET)* (*losing)
21. Wading bird caught by another one (5)
HERON
[anot]HER ON[e] (caught by)
22. Pine for young woman (4)
MISS
23. Old impressionist briefly made a comeback (4)
AGED
DEGA[s]< (impressionist, briefly, <making a comeback)
Yes great fun! Liked repercussion, Iraq, polyethylene, womenswear, many others. Thanks both.
A playful and breezy puzzle from Goliath with some very witty cluing, as always. Liked REPERCUSSION (like James), ASKEW, PERNICKETY and ESCAPOLOGIST among quite a few others.
Thanks Goliath and Oriel.