Centaur's daughter somehow ran off (10)
I believe the answer is:
horsewoman
'centaur's daughter' is the definition.
(a centaur is half human, half horse)
'somehow ran off' is the wordplay.
'off' indicates anagramming the letters.
'somehow'+'ran'='somehowran'
'somehowran' with letters rearranged gives 'HORSEWOMAN'.
(Other definitions for horsewoman that I've seen before include "Equestrienne" , "Rider" , "Eventer, perhaps" .)