The Sunday Crossword No 3260, Sunday 25 Jun 2023

ACROSS

1   Perhaps Marilyn's sweetheart to take care of a little rusty instrument (6,4) FRENCH HORN {FRENCH}{HO{Ru..y}N}

6   Betrayer turned, protecting second despot (4) TSAR {RA{S}T<=}

10 Enthrone in rumpled satinet (7) INSTATE*

11 Native Americans handing us 'avocado', 'tomato', linguistically (primarily)? (7) NAHUATL Acrostic 

12 Some prequalify in uniform (5) EQUAL [T]

13 Rain's stopped play? It's a foregone conclusion (2,7) NO CONTEST [DD]

14 A witch may have this assistant, bit of a fright (6,5) SECOND SIGHT {SECOND}{SIGHT}

18 Destructive policy: a pact must be arranged (11) APOCALYPTIC*

21 Small woodsman, one that's out for a bit (9) SLUMBERER {S}{LUMBERER}

23 Dim British king (5) BLEAR {B}{LEAR}

24 Medically assessed the 'riddle' at the outset: Everyman's got old (7) TRIAGED {The}{Ri...e}{I}{AGED}

25 Adds quality to multiple TV episodes (7) SEASONS [DD]

26 Woman essential to United Nations (4) EDNA [T]

27 Spooner's assessed judgment, briefly seeing bird (7,3) CRESTED TIT (~ tested crit to crested tit)

DOWN

1   Foundered when afield, reeling (6) FAILED*

2   Relax: that man's not still in bed, Cockney informs us (4,2) EASE UP (~ 'es up)

3   Inventor: Bach and Elgar's confused with Barber – runs off (7,7) CHARLES BABBAGE {BACH+ELGARS+BArBEr}*

4   Hullabaloo near duchy that's neglected (3,3,3) HUE AND CRY*

5   Lead operations, in charge of mysterious characters (5) RUNIC {RUN}{IC}

7   Sensible to get to grips with bit of progress that's cutting-edge (5-3) SPACE-AGE {S{PACE}AGE}

8   Sympathise with concern (6,2) RELATE TO [DD]

9   Gorges on English seafood, right away, with most of roll and vegetable (7,7) CHINESE CABBAGE {CHINES}{E}{CrAB}{BAGEl}

15 Attests to the bona fides of suspicious señoritas (9) NOTARISES*

16 Tape in difficult test case (8) CASSETTE*

17 This answer may be saline (8) SOLUTION [DD}

19 Make new arrangement for holidaymaker's destination (6) RESORT {RE-SORT}

20 For model: cheers! (6) PROSIT {PRO}{SIT}

22 Set of pulses directed one way ... or another (5) RADAR <=>

Reference List

Second = S, Small = S, British = B, Run = R, In charge = IC, English = E, Right = R, For = PRO