clacker, n.¹ — Green’s Dictionary of Slang

clacker n.¹

[clack n. (1); the noise of the teeth rattling together; note WWI milit. clacker, a chatterer, a rumourmonger]

1. the mouth.

1653		Mercurius Democritus 2-9 Feb. 338: Ye dare open, open, open your impetuous clackers, and call your Husbands by the odious Names of — Cuck, cuck, cuck, Cuck—olds.
1929		W. Winchell On Broadway 25 Sept. [synd. col.] Pointing her clackers at Hilda [she] screeched, ‘Oh look, Miss Ferguson has her bracelets in hock!’.

2. the teeth.

1950, 1965–70

in DARE.