Drink for everyone abandoning a conspirator (6)
I believe the answer is:
cassis
'drink' is the definition.
(I've seen this before)
'for everyone abandoning a conspirator' is the wordplay.
'for everyone' becomes 'U' (Universal film certificate).
'abandoning' is a deletion indicator.
'a conspirator' becomes 'cassius' (I've seen this before).
'cassius' with 'u' taken away is 'CASSIS'.
(Other definitions for cassis that I've seen before include "Liqueur made with blackcurrants" , "Blackcurrant cordial" , "Syrupy blackcurrant drink or flavouring" , "Blackcurrant syrup" , "syrup drink" .)