Drinking session, having started late, winding up (7)
I believe the answer is:
arousal
'drinking' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe there's an association between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for arousal that I've seen before include "Awakening (of emotion, etc)" , "Act of waking (someone)" , "Drinking spree" , "Act of awakening" , "heating?" .)