Central Asian wild ass (6)
I believe the answer is:
onager
'central asian wild ass' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for onager that I've seen before include "The ass is a strange orange" , "Variety of wild ass found in central Asia" , "Asiatic wild ass" , "The ass might be an odd orange colour" , "Orange Asiatic ass" .)