Green’s Dictionary of Slang

1. the throat.

1899		C. Rook Hooligan Nights 96: There was the little bleeder gettin’ black in the face froo its night-dress bein’ tied too tight round its gargler.
2023		R. Milward Man-Eating Typewriter 17: he nellies the mistress-of-ceremonies clear her gargler.

2. a drinker, a drunkard.

1967

F.J. Hardy in Great Aus. Lover Stories 36: The recognised world champion grog gargler.