Green’s Dictionary of Slang

1. (US) to lay a bet.

1905

F. Hutchison Philosophy of Johnny the Gent 6: I’ll string a little bet she’s makin' a fuss over him nex’ time you get a peek.

2. (US Und.) to ‘fix’ horseraces.

1960

P. Rabe Murder Me for Nickels (2004) 45: I’m calling about the outfit that’s stringing the bets and the races.