A spiral-horned African antelope (5)
I believe the answer is:
nyala
'a spiral-horned african antelope' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nyala that I've seen before include "Ruminant" , "Spiral-horned antelope" , "wild animal" , "Antelope of southern Africa" , "South African native" .)