Finish drinks with old fellows (5,3)
I believe the answer is:
round off
'finish' is the definition.
(I've seen this before)
'drinks with old fellows' is the wordplay.
'drinks' becomes 'round' (I've seen this before**).
'with' says to put letters next to each other.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'fellows' becomes 'ff'.
'round'+'o'+'ff'='ROUND OFF'
(Other definitions for round off that I've seen before include "Conclude" , "finish" .)