Predatory shorebird (4)
I believe the answer is:
skua
'predatory shorebird' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for skua that I've seen before include "Flyer" , "Large sea bird" , "Large predatory bird" , "Craziness" , "Auks (anag.)" .)