Too much in the drink? (9)
I believe the answer is:
overboard
'too much in the drink?' is the definition.
I can't judge whether this defines the answer.
'too much in the' is the wordplay.
'too much' becomes 'over' (over can mean to too great an extent).
'in the' becomes 'board' (I can't justify this - if you can you should give a lot more credence to this answer).
'over'+'board'='OVERBOARD'
Can you help me to learn more?
(Other definitions for overboard that I've seen before include "Man . . . . . . . . . - launch the lifeboat!" , "(Fall) into the sea" , "having made a splash" , "Very enthusiastic" , "excess" .)