Cool drink, half of beer (5)
I believe the answer is:
super
'cool' is the definition.
(thesaurus)
'drink half of beer' is the wordplay.
'drink' becomes 'sup' (I've seen this before).
'half of' indicates taking half.
'beer' cut in half is 'er'.
'sup'+'er'='SUPER'
(Other definitions for super that I've seen before include "Fantastic" , "Wicked" , "Brilliant" , "Top" , "Excellent - small-part actor" .)