Slow wild birds (4)
I believe the answer is:
owls
'birds' is the definition.
(owl is a kind of bird)
'slow wild' is the wordplay.
'wild' indicates an anagram.
'slow' with letters rearranged gives 'OWLS'.
(Other definitions for owls that I've seen before include "Wise old birds - quite slow" , "Slow kind of birds" , "Night birds" , "Types incredibly wise" , "Nocturnal bird" .)