Beat most of the drink (5)
I believe the answer is:
whisk
'beat' is the definition.
(whisking is a kind of beating)
'most of the drink' is the wordplay.
'most of' means to remove the last letter.
'the drink' becomes 'whisky' (whisky is a kind of drink).
'whisky' with its final letter taken away is 'WHISK'.
(Other definitions for whisk that I've seen before include "Kitchen utensil" , "Kitchen mixer" , "Whipping utensil" , "Egg beater" , "Food mixer" .)