Green’s Dictionary of Slang

to fawn, to flatter.

1606		P. Holland (trans.) Suetonius’s Historie of Twelve Caesars (1899) II 188: He was besides of a wonderfull glavering nature and given to flatteries.
c.1698		B.E. Dict. Canting Crew n.p.: Glaver to Fawn and Flatter. A Glavering Fellow, a False Flattering Fellow.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].