Nut race around mythical creature (7)
I believe the answer is:
centaur
'mythical creature' is the definition.
(centaur is a kind of mythical creature)
'nut race around' is the wordplay.
'around' is an anagram indicator.
'nut'+'race'='nutrace'
'nutrace' with letters rearranged gives 'CENTAUR'.
(Other definitions for centaur that I've seen before include "Mythical creature with the head of a man and the body of a horse" , "Mythical creature, half-man, half-horse" , "Mythical creature with horse's body and man's upper torso" , "Mythical beast, half horse and half man" , "Greek mythical creature" .)