Wildebeests (4)
I believe the answer is:
gnus
'wildebeests' is the definition.
('gnu' can be a synonym of 'wildebeest')
This is the entire clue.
(Other definitions for gnus that I've seen before include "Wildebeests" , "African runners" , "Big game" , "Animals" , "Snug (anag) -- wildebeest" .)