Horse's mate threatening to kick us (8)
I believe the answer is:
palomino
'horse's' is the definition.
(palomino is a kind of horse)
'mate threatening to kick us' is the wordplay.
I cannot quite understand how this works, but
'mate' could be 'pal' (I've seen this before) and 'pal' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for palomino that I've seen before include "Golden horse with pale mane" , "Equine" , "Golden horse with white mane and tail" , "White-maned horse of the southwest USA" , "colt?" .)