Wasted evening? (5-2)
I believe the answer is:
booze-up
'wasted evening?' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
This is all the clue.
Can you help me to learn more?
(Other definitions for booze-up that I've seen before include "Drinking spree" , "Bout of serious drinking" , "Heavy drinking session" .)