Positive quantity of booze will be supplied by party (3-2)
I believe the answer is:
can-do
'positive' is the definition.
(I've seen this before)
'quantity of booze will be supplied by party' is the wordplay.
I cannot really understand how this works, but
'quantity' could be 'can' (can is a kind of quantity) and 'can' is present in the answer.
'of' could be 'o' and 'o' is located in the answer.
A single letter 'd' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for can-do that I've seen before include "Positive" , "Positive-thinking" , "Showing willingness to get the job done" .)