Very easy, indeed, I thought – as fast as I’ve solved any Indy puzzle this year – but not solved correctly, thanks, Neal H.
* = anagram
1 C (HEAP)O
5 TEST CASE (a sect set)*
9 LITTLE HAMPTON (phantom)* In Sussex
10 ME (A) N
11 SCRAP E H O ME
12 D(E)AD PA N
14 OO LONG
16 CASTRO (actors)* Fidel or, indeed, Raul
18 SH ELVES
20 VIC (ER) E GENT (No, it is not! Thanks, Neal H, for pointing out that this should be VICEGERENT)
23 A RUM
24 SOME LIKE IT HOT 1950s film
25 RE STORE R
26 TUN (DR) A
DOWN
2 HA (L BE) RD
3 AT TEN DANT(e)
4 (b)OGLES
5 T (EHER) AN (here)* &lit also, I guess
6 SEMAPHORE (share poem)*
7 CAT CH
8 SANDMAN hidden
13 PROP (ELL) ER
15 LEVI (N)ATHAN
17 A T IS SUE
18 SNEAKER Double definition
19 S (AUNT) E R
21 E (MME) T
22 TA (IN) T
You fell into the same trap that I did of putting “viceregent” for 20 across, but it’s actually “vicegerent”. At first, I thought this was an error in the online version, but then I checked the definition and there really is such a word. I think you could make out a case for “viceregent” being a viable alternative.