Spoil drink? That's the limit! (6)
I believe the answer is:
margin
'the limit' is the definition.
(thesaurus)
'spoil drink?' is the wordplay.
'spoil' becomes 'mar' (synonyms).
'drink?' becomes 'gin' (gin is an alcoholic drink).
'mar'+'gin'='MARGIN'
'that's' acts as a link.
(Other definitions for margin that I've seen before include "Blank space around the edge" , "bank" , "Edge, border, fringe" , "Border or leeway" , "Blank space around a text" .)