When the idiot stands a drink, don’t accept it (4,2)
I believe the answer is:
pass up
'don't accept it' is the definition.
I can't tell whether this defines the answer.
'when the idiot stands a drink' is the wordplay.
I cannot really see how this works, but
'when' could be 'as' (eg 'when I walked' means 'as I walked') and 'as' is found within the answer.
'drink' could be 'sup' (to sup is to drink) and 'sup' is found in the answer.
A single letter 'p' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for pass up that I've seen before include "forego" , "Refuse - reject" , "col?" , "Showing neglect" , "Miss" .)