Long-horned wild goat (4)
I believe the answer is:
ibex
'long-horned wild goat' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ibex that I've seen before include "Mountain-goat" , "Large-horned mountain goat" , "Sure-footed type" , "Mountain goat with curving horns" , "Sure-footed climber" .)