Degenerate is modest about these days? (8)
I believe the answer is:
decadent
'degenerate' is the definition.
(I know that degenerate can be written as decadent)
'modest about these days?' is the wordplay.
'modest' becomes 'decent' (I've seen this before).
'about' is an insertion indicator.
'these days?' becomes 'AD' (as in Anno Domini, after Christ).
'decent' going around 'ad' is 'DECADENT'.
'is' is the link.
(Other definitions for decadent that I've seen before include "Morally corrupt" , "Reflecting a state of moral decline" , "Degenerate" , "Sybaritic" , "going off" .)