Drench with liquid (5)
(Other definitions for souse that I've seen before include "Pickle - drunkard" , "Marinate" , "Wash" , "thoroughly wet" , "Drench" .)
'drench with liquid' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for douse that I've seen before include "Drench; extinguish" , "duck in water" , "Drench with liquid" , "Drench with water" , "Smother with water" .)