Hairdo of a small-horse follower (8)
I believe the answer is:
ponytail
'hairdo' is the definition.
(I know that ponytail is a type of hairdo)
'a small-horse follower' is the wordplay.
'a small horse' becomes 'pony' (I've seen this in another clue).
'follower' becomes 'tail' (tail is a kind of follower).
'pony'+'tail'='PONYTAIL'
'of' is the link.
(Other definitions for ponytail that I've seen before include "Arrangement of locks" , "Plain toy (anag) - hairstyle" , "Drawn-back hairstyle" , "Drawn-back hair style" , "hairdo" .)