Drink lager mixed with European beverage (6,3)
I believe the answer is:
ginger ale
'beverage' is the definition.
(ginger ale is a kind of beverage)
'drink lager mixed with european' is the wordplay.
'drink' becomes 'gin' (gin is a kind of drink).
'mixed with' indicates an anagram.
'european' becomes 'e' (abbreviation e.g. EU).
'lager' mixed up with 'e' makes 'gerale'.
'gin'+'gerale'='GINGER ALE'
(Other definitions for ginger ale that I've seen before include "One drink" , "Fizzy drink" , "pop" , "Spicy, sweetened non-alcoholic drink" , "It won't make you drunk!" .)