Corrupt worthy accepts promotion (8)
I believe the answer is:
decadent
'corrupt' is the definition.
(thesaurus)
'worthy accepts promotion' is the wordplay.
'worthy' becomes 'decent' (I can't explain this - if you can you should believe this answer much more).
'accepts' means one lot of letters goes inside another.
'promotion' becomes 'ad' (ad is a kind of promotion).
'decent' going around 'ad' is 'DECADENT'.
Can you help me to learn more?
(Other definitions for decadent that I've seen before include "Self-indulgent or immoral" , "Morally corrupt" , "base?" , "Abandoning principles" , "Showing moral decline" .)