Bison feature (4)
I believe the answer is:
hump
'bison feature' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hump that I've seen before include "Feature of llama, camel" , "Carry (heavy loads) (informal)" , "Protuberance on back, road etc" , "Characteristic of camel" , "Part of a camel" .)