Opposed to a holy man pocketing reward (7)
I believe the answer is:
against
'opposed to' is the definition.
(thesaurus)
'a holy man pocketing reward' is the wordplay.
'holy man' becomes 'st'.
'pocketing' is an insertion indicator.
'reward' becomes 'gain' (I've seen this before).
'a'+'st'='ast'
'ast' going around 'gain' is 'AGAINST'.
(Other definitions for against that I've seen before include "In competition with" , "Not in favour of" , "Opposite to" , "Con" , "Placed in direct contact with" .)