Collect drinks cheerfully (5,2)
I believe the answer is:
round up
'collect' is the definition.
(rounding up is a kind of collecting)
'drinks cheerfully' is the wordplay.
'drinks' becomes 'round' (I've seen this before).
'cheerfully' becomes 'up' (I can't explain this - if you can you should give a lot more credence to this answer).
'round'+'up'='ROUND-UP'
Can you help me to learn more?
(Other definitions for round up that I've seen before include "rally" , "Use less accurate figure" , "gathering" , "Group" , "collection of data" .)