Wally. It`s an ugly slang word - not one I (or you) would ever use! I imagine it means drinking straight from the bottle.
Don`t tell anyone - I still haven`t got 15ac !
PS What`s happened to Old Gal??
15a. the first letter and the last 3 = a word meaning "to satisfy a desire (or appetite)". the remaining 3 letters = to lapse or wander from the straight and narrow. Whole word = Make cuts. HOpe this does it.