Wild goat (4)
I believe the answer is:
ibex
'wild goat' is the definition.
(ibex is a kind of wild goat)
This is all the clue.
(Other definitions for ibex that I've seen before include "Wild goat with large recurved horns" , "Sure-footed type" , "Mountain animal" , "Mountain-goat" , "being nimble-footed" .)