Rod for fish (5)
I believe the answer is:
perch
This clue is a double definition.
'rod' is the first definition.
('perch' can be a synonym of 'rod')
'fish' is the second definition.
(perch is a kind of fish)
'for' is the link.
(Other definitions for perch that I've seen before include "Fish; pole" , "old measure of land" , "Rest (as a bird)" , "Rod on which bird roosts" , "[SOMETHING FISHY]" .)