Fish turning bad? (3)

I believe the answer is:

dab

'fish' is the definition.
(dab is a type of fish)

'turning bad' is the wordplay.
'turning' says the letters should be written backwards.
'bad' backwards is 'DAB'.

(Other definitions for dab that I've seen before include "A small fish - bad one" , "Apply light touches of colour to the fish" , "A fish; light touch" , "Digital radio" , "Gently wipe" .)

I've seen this clue in the Evening Standard.

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