All-powerful men opt into corruption (10)
I believe the answer is:
omnipotent
'all-powerful' is the definition.
('omnipotent' can be a synonym of 'all-powerful')
'men opt into corruption' is the wordplay.
'corruption' indicates anagramming the letters.
'men'+'opt'+'into'='menoptinto'
'menoptinto' anagrammed gives 'OMNIPOTENT'.
(Other definitions for omnipotent that I've seen before include "All-powerful" , "Almighty" .)