Expert fish worker (3,4)

I believe the answer is:

dab hand

'expert' is the definition.
(I've seen this before)

'fish worker' is the wordplay.
'fish' becomes 'dab' (I've seen this before).
'worker' becomes 'hand' (hand is a kind of worker).
'dab'+'hand'='DAB HAND'

(Other definitions for dab hand that I've seen before include "An informal expert such as band had" , "Barely wash" , "cursory wash?" , "Past master" .)

I've seen this clue in The Guardian and The Telegraph.

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