Go for a drink (3)
I believe the answer is:
pop
I believe this is a double definition.
'go' is the first definition.
(I know that pop is a type of go)
'a drink' is the second definition.
(pop is a kind of drink)
'for' acts as a link.
(Other definitions for pop that I've seen before include "Thus goes the musical weasel" , "Youthful music, dad(3)" , "Palindrome of music for the young" , "Cartoon sailor (showing amazement?)" , "'American Dad'!" .)