Prophet embraces mission to isolate (9)
I believe the answer is:
sequester
'isolate' is the definition.
(I know that sequester is a more specific form of the action isolate)
'prophet embraces mission' is the wordplay.
'prophet' becomes 'seer' (both can mean someone who tells the future).
'embraces' is an insertion indicator.
'mission' becomes 'quest' (a quest is a mission or search).
'seer' enclosing 'quest' is 'SEQUESTER'.
'to' acts as a link.
(Other definitions for sequester that I've seen before include "Take aside" , "Isolate or hide away (something or someone)" , "Remove; confiscate (property)" , "Appropriate" , "Legally confiscate" .)