Nocturnal birds of prey (4)
I believe the answer is:
owls
'nocturnal birds of prey' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for owls that I've seen before include "Night birds" , "Avian symbols of wisdom" , "Nocturnal birds" , "Members of Parliament" , "Slow kind of birds" .)