Seafood payment method (3)
I believe the answer is:
cod
This clue is a double definition.
'seafood' is the first definition.
(cod is a kind of seafood)
'payment method' is the second definition.
(cash on delivery)
(Other definitions for cod that I've seen before include "Not a real" , "Initially, pay when you get the goods" , "No payment in advance" , "A foolish sort of a fish" , "mock" .)