Scout occasionally drunk (3)
I believe the answer is:
sot
'drunk' is the definition.
('sot' can be a synonym of 'drunk')
'scout occasionally' is the wordplay.
'occasionally' indicates alternate letters.
The alternate letters of 'scout' are 'SOT'.
(Other definitions for sot that I've seen before include "Boozer" , "drunk" , "Lush" , "One's often intoxicated" , "Habitual drinker" .)