Crossword Genius

Ace detectives may be bitter (4)

Ross

I believe the answer is:

acid

'be bitter' is the definition.
(acid can mean bitter-tasting)

'ace detectives' is the wordplay.
'ace' becomes 'a' (abbreviation).
'detectives' becomes 'CID' (abbreviation for Criminal Investigation Department).
'a'+'cid'='ACID'

'may' is the link.

(Other definitions for acid that I've seen before include "Sour - vitriolic" , "Polluted precipitation" , "Caustic and biting" , "So-called drug" , "bad rain" .)

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