Bobby put in a prune making drink (7)
I believe the answer is:
alcopop
'drink' is the definition.
(I've seen this before)
'bobby put in a prune' is the wordplay.
'bobby' becomes 'cop' (I've seen this in other clues).
'put in' is an insertion indicator.
'prune' becomes 'lop' (synonyms).
'a'+'lop'='alop'
'cop' put inside 'alop' is 'ALCOPOP'.
'making' acts as a link.
(Other definitions for alcopop that I've seen before include "drink young people like" , "A mix of alcohol and soft drink" , "drink for young adult" , "Alcoholic beverage that tastes like a soft drink (inf)" , "Polo cap (anag.)" .)