Cyclist or equestrian (5)
I believe the answer is:
rider
'cyclist or equestrian' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rider that I've seen before include "H. - Haggard, English novelist (She, etc)" , "One backing a horse" , "Jury's recommendation" , "Supplementary clause" , "in the dressing room before the show?" .)