Straight-horned antelope (4)
I believe the answer is:
oryx
'straight-horned antelope' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oryx that I've seen before include "Large African antelope with long straight horns" , "African long-horned grazer" , "Animal" , "African native" , "creature" .)