About to wake up and drink (7)
I believe the answer is:
carouse
'drink' is the definition.
(thesaurus)
'about to wake up' is the wordplay.
'about' becomes 'ca' (circa).
'to wake up' becomes 'rouse' (rouse can mean to wake up).
'ca'+'rouse'='CAROUSE'
'and' acts as a link.
(Other definitions for carouse that I've seen before include "Engage in boisterous, drunken merry-making" , "booze" , "Celebrate noisily" , "Drink and make merry" , "Drink a lot" .)