Red deer (4)
I believe the answer is:
hind
'red deer' is the definition.
(hind is a kind of red deer)
This is the entire clue.
(Other definitions for hind that I've seen before include "Female animal; at the back" , "Be in front of this farm-worker" , "A female deer, situated at the back?" , "Rear - female deer" , "Female red deer" .)