SLORMGORM kicks off the week…
A fun puzzle with some amusing surfaces. There is a backwards UNCLE Nina almost halfway down, but I suspect it's unintended.
Thanks SLORMGORM!

ACROSS
7. Part of song leaving one filled with ecstasy (4)
AREA
ARIA (song, leaving I (one) filled with E (ecstasy))
8. Unruly masses plot to get those involved in purge (5,5)
EPSOM SALTS
10. Trump is one mostly sluggish republican (6)
LEADER
LEADE[n] (sluggish, mostly) + R (republican)
11. Go off on a conservative or revolutionary? (8)
ROTATORY
ROT (go off) on A + TORY (conservative)
12. Toothy type in bondage gear cops left by lake (8)
CHAINSAW
CHAINS (bondage gear) + [l]AW (cops, left by L (lake))
13. Pa is tired by his wife and children ultimately (3,3)
OLD MAN
OLD (is tired) by MA (his wife) and [childre]N (ultimately)
15. Is April honest about affairs of the heart? (13)
RELATIONSHIPS
(IS APRIL HONEST)* (*about)
18. Rifleman at front going after high-flyer? (6)
SNIPER
R[ifleman] (at front) going after SNIPE (high-flyer)
20. Cops on holiday chill with heartless robbers (8)
OFFICERS
OFF (on holiday) + ICE (chill) with R[obber]S (heartless)
22. Kick back, Spooner is telling you, and drink (4,4)
ROOT BEER
"boot rear" = ROOT BEER (kick back, "Spooner is telling you")
24. Very entertained (initially) during assembly (6)
REALLY
E[ntertained) (initially) during RALLY (assembly)
25. I tucked into a porridge cooked for a beast (7,3)
PRAIRIE DOG
I tucked into (A PORRIDGE)* (*cooked)
26. One posted over in Georgia close to Roswell (4)
GOAL
(O (over) in GA (Georgia)) + [Roasel]L (close to)
DOWN
1. Inexperienced horse will unseat one flapper (5,5)
GREEN HERON
GREEN (inexperienced) + HERO[i]N (horse, will unseat I (one))
2. Monkey being sick must be visited by doctor (8)
MANDRILL
(MAN (being) + ILL (sick)) visited by DR (a doctor)
3. Try on tops from Tiffany’s and single-breasted suit (6)
HEARTS
HEAR (try) on T[iffany] S[ingle-breasted] (tops from)
4. European gesture primarily stirs passions (8)
EMOTIONS
E (European) + MOTION (gesture) + S[tirs] (primarily)
5. Having gone away from island, had fun in Split (6)
PARTED
PART[i]ED (had fun, having gone away from I (island))
6. Thugs’ leader punches teacher in prison (4)
STIR
T[hug] (leader) punches SIR (teacher)
9. Record lout was playing could be Yellow (5-8)
STRAW-COLOURED
(RECORD LOUT WAS)* (*playing)
14. Isn’t Laura going out with a chap from Perth? (10)
AUSTRALIAN
(ISNT LAURA)* (*going out) with A
16. Retired nun tried to become something different (6,2)
TURNED IN
(NUN TRIED)* (*to become something different)
17. Where the Light Brigade were holding the reins? (2,6)
IN CHARGE
Double (cryptic) definition
19. Russian autocrat hiding son in lodges (4,2)
PUTS IN
PUTIN (Russian autocrat) hiding S (son) in
21. Fury shown by group of footballers and right-winger? (6)
FARAGE
RAGE (fury) shown by FA (group of footballers)
Nigel Farage
23. Men holding a skater’s first blades (4)
OARS
OR (men) holding (A + S[kater] (first))
Very solid, thanks both.
Liked Australian and Farage (the clue, that is)
Very enjoyable, thank you. There were one or two I couldn’t parse (one was CHAINSAW), resulting in a “D’oh” or two when I came here. I didn’t know there were green herons, nor had I heard of ROTATORY — wouldn’t rotary do the same job?
Yes, this was a fine puzzle with a good Spoonerism, lovely anagrams and fine surfaces.
I liked STRAW-COLOURED, RELATIONSHIPS, AUSTRALIAN and FARAGE.
There’s a small slip, Teacow – 25a needs the ‘i’ tucked into ‘a porridge’ to form PRAIRIE DOG.
Thanks to Slormgorm and Teacow.