Cain reformed? Member of the clergy's wrong (10)
I believe the answer is:
inaccurate
'wrong' is the definition.
(associated in meaning)
'cain reformed? member of the clergy's' is the wordplay.
'reformed?' indicates an anagram.
'member of the clergy' becomes 'curate' (assistant to a priest).
'cain' with letters rearranged gives 'inac'.
'inac'+'curate'='INACCURATE'
(Other definitions for inaccurate that I've seen before include "not hitting all the right notes?" , "wrong" , "Unreliable" .)