Horse's moderate pace (4)
(Other definitions for canter that I've seen before include "Trance (anag) - horse's pace" , "Move at an easy gallop" , "Lope" , "Gallop easily" , "Gentle movement in bay, say" .)
(Other definitions for trot that I've seen before include "Radical socialist (abbr) - horse gait" , "Horse's steady pace" , "(Horse's) pace faster than a walk" , "An elderly woman" , "Run with short steps" .)