Sheila turned prophet (6)
I believe the answer is:
elisha
'prophet' is the definition.
(Hebrew prophet)
'sheila turned' is the wordplay.
'turned' indicates an anagram.
'sheila' is an anagram of 'ELISHA'.
(Other definitions for elisha that I've seen before include "Prophet; Thirteen across (anag.)" , "Hebrew prophet" , "Elijah's successor" , "Old Testament prophet" .)