Scoundrel downing good Beaujolais? (5)
I believe the answer is:
rouge
'beaujolais?' is the definition.
(type of red wine - 'rouge' is 'red' in French)
'scoundrel downing good' is the wordplay.
'scoundrel' becomes 'roue' (historical term for a debauched man).
'downing' indicates putting letters inside (to down food or drink is to swallow it quickly).
'good' becomes 'g' (abbreviation).
'roue' enclosing 'g' is 'ROUGE'.
(Other definitions for rouge that I've seen before include "Cosmetic for reddening cheeks" , "Face-reddening cosmetic" , "Polish used by jewellers" , "struggle at Eton" , "Cheek colouring" .)