Garments for certain racehorses? (7)
I believe the answer is:
jumpers
I believe this clue is a double definition.
'garments' is the first definition.
(jumper is a kind of garment)
'certain racehorses?' is the second definition.
'for' is the link.
(Other definitions for jumpers that I've seen before include "They warm you up" , "Garments" , "get you going when powerless (in > play)" , "suitable for spring?" .)