Green’s Dictionary of Slang

a pickpocket or cut-purse, spec. an experienced one who demands a share of their younger peers’ profits.

1602		Rowlands Greenes Ghost Haunting Conicatchers B4: These haue their cloyers and fillowers, which are verie troublesome to them, for thye can no sooner draw a bung but these come in for their tenths, which are generally tearm snapping, or snappage.
1611		Middleton & Dekker Roaring Girle V i: There’s a cloyer, or snap, that dogs any new brother in that trade, and snaps will have half in any booty.
1659		Catterpillers of this Nation Anatomized 2: The Filer or Cloyer (alias) a common Thief .
1688		R. Holme Academy of Armory Ch. iii item 68c: Canting Terms used by Beggars, Vagabonds, Cheaters, Cripples and Bedlams. [...] Cloyers, thieves, Purloyners.
c.1698		B.E. Dict. Canting Crew n.p.: Cloyers, c. Thieves, Robbers, Rogues.
1725		New Canting Dict.
1737		Pope Mother Gin 19: Wearied Cloyers, who recline In grassy fields suburbian all day-light, And snore away the filching toils of night.
1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1822		R. Nares Gloss. (1888) I 168: cloyer. A term in the slang, or conventional language, of the thieves of old time, for one who intruded on the profits of young sharpers, by claiming a share.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
c.1850		Duncombe New and Improved Flash Dict.