Food from river is fish (7)
I believe the answer is:
rissole
'food' is the definition.
(rissole is a kind of food)
'river is fish' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'fish' becomes 'sole' (sole is a kind of fish).
'r'+'is'+'sole'='RISSOLE'
'from' is the link.
(Other definitions for rissole that I've seen before include "faggot" , "Lorises (anag)" , "Sil rose for the meatball" , "Losers I find in the chopped meat dish" , "Fried and breadcrumbed dish" .)