Following live deer? (6)
I believe the answer is:
'following' is the definition.
'live deer?' is the wordplay.
'live' becomes 'be' ('be' can be a synonym of 'live').
'deer?' becomes 'hind' (hind is a kind of deer).
(Other definitions for behind that I've seen before include "Hidden by; in arrears" , "Seat" , "support" , "Astern" , "Serving time" .)