Horse galloped around ring (4)
I believe the answer is:
roan
'horse' is the definition.
(roan is a kind of horse)
'galloped around ring' is the wordplay.
'galloped' becomes 'ran' (I've seen this in other clues).
'around' indicates putting letters inside.
'ring' becomes 'O' (O is the shape of a ring).
'ran' placed around 'o' is 'ROAN'.
(Other definitions for roan that I've seen before include "nag" , "Of horse, with coat sprinkled with white or grey hairs" , "Horse with coat speckled with white or grey" , "Reddish-coloured horse" , "(Horse) white-sprinkled coat" .)