Spiral-horned ruminant (5)
I believe the answer is:
eland
'spiral-horned ruminant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eland that I've seen before include "Large African deer with short spiral horns" , "Ruminant" , "Large spiral-horned African antelope" , "Laden (anag.); antelope" , "game animal" .)