They give a hoot (4)
I believe the answer is:
owls
'they give a hoot' 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 "Nocturnal hooters?" , "Night birds" , "Slow (anag) -- birds of prey" , "Slow sort of birds" , "Types incredibly wise" .)