Green’s Dictionary of Slang

1. a lookout for a criminal gang [he stands and watches].

1610

Rowlands Martin Mark-all 53: This Lawrence had beene [...] cast out of seruice, and so was faine to liue among the wicked, sometimes a stander for the padder, sometimes a verser for the cony-catcher, sometimes a stale for a foyst, but most commonly an Apple-squire for a trudging house.

2. (US) the victim of a confidence trickster [he ‘stands for’ the trick].

1922

Edwardsville Intelligencer (IL) 14 Sept. 4/4: The Flappers’ Dictionary [...] Stander: Victim of a female grafter.

3. (UK und.) a parked car with no-one in it.

1935

Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 10: Stander: Unattended motor car.