Spirited horse (4)
I believe the answer is:
arab
'spirited horse' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for arab that I've seen before include "Fine horse breed" , "Small, lively breed of horse" , "race" , "One from the Middle East, say" , "Horse of a breed originating in the Middle East" .)