Prophet of doom religious person claims exploit (9)
I believe the answer is:
defeatist
'prophet of doom' is the definition.
(thesaurus)
'religious person claims exploit' is the wordplay.
I cannot really see how this works, but
'exploit' could be 'feat' (synonyms) and 'feat' is located in the answer.
'person' could be 'deist' (deist is a kind of person) and 'deist' is located in the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for defeatist that I've seen before include "One who always expects failure" , "One expects frustration" , "With this attitude, one is resigned to failure" , "Unnecessarily pessimistic" , "expecting to fail" .)