Fish paid for at the door (3)

I believe the answer is:

cod

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

I cannot understand how the rest of the clue works.

(Other definitions for cod that I've seen before include "faked" , "catch!" , "Payment arrangement" , "Hoax (sl.); fish" , "mock" .)

I've seen this clue in The Telegraph and The Globe and Mail.

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