Garments take time for horse discipline (8)
I believe the answer is:
dressage
'horse discipline' is the definition.
'dressage' can be an answer for 'discipline' (I have seen 'Equestrian discipline' mean 'dressage' so perhaps 'discipline' could also mean 'dressage'). I'm not sure about the 'horse' bit.
'garments take time' is the wordplay.
'garments take' becomes 'dress' (I am not sure about this - if you are sure you should believe this answer much more).
'time' becomes 'age' (an age is a period of time).
'dress'+'age'='DRESSAGE'
'for' is the link.
Can you help me to learn more?
(Other definitions for dressage that I've seen before include "Part of equestrian event" , "Equestrian performance" , "Olympic event" , "Manoeuvres of a horse in response to body signals by its rider" , "The training of a horse in manoeuvres" .)