Distinctive horse (4)
I believe the answer is:
roan
'distinctive horse' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for roan that I've seen before include "Type of 17's coat colouring" , "Horse with main colour interspersed with hairs of another" , "Nora (anag) - horse" , "Bay spotted" , "nag" .)