Payment method for seafood (3)
I believe the answer is:
cod
This clue is a double definition.
'payment method' is the first definition.
(cash on delivery)
'seafood' is the second definition.
(cod is a kind of seafood)
'for' acts as a link.
(Other definitions for cod that I've seen before include "Fish noted for liver oil" , "Tasty fish or slangy nonsense" , "Hoax (sl.); fish" , "Cash on delivery, in short, for this fish" , "One caught in the deep maybe" .)