Green’s Dictionary of Slang

1. (US Und.) a waistcoat or waistcoat watch pocket.

1851		G. Thompson Jack Harold 60: I got a pair of flash kicks, a tog and cady too, / A gallus jerve, a pair of squills so polish’d and so new.
1902		Wash. Times (DC) 14 Sept. 10/4: Jerve— A vest pocket.
1909		F.H. Tillotson How I Became a Detective 92: Jerve – A vest pocket.
1914		Jackson & Hellyer Vocab. Criminal Sl. 49: jerve [...] A vest pocket.
1933		Ersine Und. and Prison Sl. 47: jerv, n. A vest pocket.

2. (US Und., also jerver) in a pickpocket team, the one who actually does the stealing.

1909		F.H. Tillotson How I Became a Detective 92: Jerver – A pickpocket.
1914		Jackson & Hellyer Vocab. Criminal Sl. 49: jerve [...] the ‘tool’; the ‘wire’; the ‘claw’ in a gun mob.