Skilfully modified idolatry (8)
I believe the answer is:
adroitly
'skilfully' is the definition.
(I've seen this before)
'modified idolatry' is the wordplay.
'modified' is an anagram indicator.
'idolatry' with letters rearranged gives 'ADROITLY'.
(Other definitions for adroitly that I've seen before include "Idolatry (anag) -- with skill" , "With skill - dilatory (anag)" , "Quickly and skilfully" , "With deftness" , "far from clumsily" .)