Green’s Dictionary of Slang

(UK Und.) of a gang member, to keep watch.

1740		Ordinary of Newgate Account of the Behaviour, Confession, and Dying Words of [...] Mary Young in Rawlings Criminal Biogs. of the 18th Cent. (1992) 126: Now it was so contriv’d by the rest of the Gang, that one should go before as a Scout, and bring Word to the supposed Footman in what Part of the Meeting set the rummest Froes; and likewise to Saweer clearly, (that is, to keep a good look out) that they should have Vid Loges (repeating Watches) by their Side.
1764		Bloody Register III 170: Likewise to saweer clearly (i.e. to keep a good look-out).