Ostrich or kangaroo
I believe the answer is:
biped
'ostrich or kangaroo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for biped that I've seen before include "Two legged creature" , "Two-footed creature" , "One standing on two feet" , "One walking on two legs" , "Girl, say" .)