Drink too much to exercise (4)
I believe the answer is:
tope
'drink too much' is the definition.
(I've seen this in another clue)
'to exercise' is the wordplay.
'exercise' becomes 'pe' (Physical Education).
'to'+'pe'='TOPE'
(Other definitions for tope that I've seen before include "Drink too much like poet" , "Small grey requiem shark" , "Drink to excess" , "Drink a lot like poet" , "plantation?" .)