Atlantic catch (3)
I believe the answer is:
cod
'atlantic catch' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cod that I've seen before include "Tasty fish or slangy nonsense" , "A fish; a hoax (slang)" , "Pull the leg of - a fish?" , "Initially, pay when you get the goods" , "Common food fish" .)