Three-beat gait
I believe the answer is:
canter
'three-beat gait' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for canter that I've seen before include "Lope" , "Gait between a trot and a gallop" , "Gallop easily" , "Horse gait quicker than 9 across" , "Move at an easy gallop" .)