Ruin alcoholic drink (6)
I believe the answer is:
scotch
I believe this clue is a double definition.
'ruin' is the first definition.
(I know that ruin is a kind of scotch)
'alcoholic drink' is the second definition.
(Other definitions for scotch that I've seen before include "Put an end to - in Caledonia?" , "Type of egg" , "Prevent -- frustrate" , "providing nursery facility in school" , "Whisky (not whiskey!)" .)