Fish-eating bird of prey (6)
I believe the answer is:
osprey
'fish-eating bird of prey' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for osprey that I've seen before include "Fish-eater" , "Flyer" , "Fish-eating raptor" , "Bird from an outsize victim" , "Marine bird of prey" .)