Row around river for fish (5)
I believe the answer is:
sprat
'fish' is the definition.
(sprat is a kind of fish)
'row around river' is the wordplay.
'row' becomes 'spat' (spat is a kind of row).
'around' indicates putting letters inside.
'river' becomes 'r'.
'spat' enclosing 'r' is 'SPRAT'.
'for' acts as a link.
(Other definitions for sprat that I've seen before include "'Set a . . . . . to catch a whale'" , "Mackerel bait?" , "Strap up the small fish" , "Small sea fish" , "chap on a fat-free diet" .)