Payment on delivery of fish (3)
I believe the answer is:
cod
I believe this is a double definition.
'payment on delivery' is the first definition.
(abbreviation for cash on delivery)
'fish' is the second definition.
(type of fish)
'of' is the link.
(Other definitions for cod that I've seen before include "Play joke on" , "Kid" , "A joke of a fish?" , "Cash on delivery (abbr.)" , "Tasty fish or slangy nonsense" .)