She disagrees that punishment deters sin (9)
I believe the answer is:
dissenter
'she disagrees that punishment' is the definition.
The definition suggests a singular noun which matches the answer.
'deters sin' is the wordplay.
'deters sin' can be anagrammed to 'DISSENTER'.
Though, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for dissenter that I've seen before include "one not C of E" , "One not agreeing" , "One who differs among residents" , "One expressing disagreement" , "One who disagrees among residents" .)