Many stir drink excessively (7)
I believe the answer is:
carouse
'drink excessively' is the definition.
'carouse' can be an answer for 'drink' (thesaurus). I'm not sure about the 'excessively' bit.
'many stir' is the wordplay.
I cannot really see how this works, but
'many' could be 'c' (C is the Roman numeral for 100) and 'c' is found in the answer.
'stir' could be 'arouse' (arousing is a kind of stirring) and 'arouse' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for carouse that I've seen before include "Celebrate noisily" , "booze" , "Roister" , "Drink freely and noisily" , "Take a course to party wildly" .)