Also have wine, as discussed, when needed (2,3)
I believe the answer is:
ad hoc
'when needed' is the definition.
(ad hoc can mean when needed)
I can't explain the remainder of the clue.
(Other definitions for ad hoc that I've seen before include "Applied to a particular situation" , "specific occasion" , "Latin notation - for a specific purpose" , "For one particular purpose" , "For a specific purpose, say an arrangement" .)