To beat. Fag the bloss; beat the wench; Cant. A fag also means a boy of an inferior form or class, who acts as a servant to one of a superior, who is said to fag him, he is my fag; whence, perhaps, fagged out, for jaded or tired. To stand a good fag; not to be soon tired.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
fadge * faggerNathan Bailey's 1721 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes