Left in the chilled fish (3)

I believe the answer is:

cod

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

I can't explain the rest of the clue.

(Other definitions for cod that I've seen before include "Kid" , "Large sea fish- it's a sham" , "North Atlantic fish" , "to be paid for when it arrives" , "Cash on delivery for hoax" .)

I've seen this clue in the Evening Standard.

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