Horse's hindquarter (6)
I believe the answer is:
haunch
'horse's hindquarter' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for haunch that I've seen before include "rump" , "Hip and buttock" , "Leg and loin of meat" , "Let and loin as food, as of deer" , "Human hip" .)