Prolong beer-drinking group (6,3)
I believe the answer is:
string out
'prolong' is the definition.
(I've seen this in another clue)
'beer-drinking group' is the wordplay.
'beer' becomes 'stout' (type of beer).
'drinking' means one lot of letters goes inside another (inserted letters are consumed or drunk).
'group' becomes 'ring' (a ring is a criminal organisation).
'stout' placed around 'ring' is 'STRING OUT'.
(Other definitions for string out that I've seen before include "Prolong" , "Extend" .)