Habitual drunkard (3)
I believe the answer is:
'habitual drunkard' is the definition.
(sot can mean a drunken person)
This is all the clue.
(Other definitions for sot that I've seen before include "One drinks" , "One's often intoxicated" , "Habitual drunkard" , "A chronic drinker" , "Toper" .)