Green’s Dictionary of Slang

1. a paid assignment, usu. to murder someone but also sometimes to get them into a less severe form of difficulty; thus put/take out a contract on v., to arrange to have someone killed; contract killer n., a killer for hire.

1891		F.W. Carew Autobiog. of a Gipsey 434: There’s more ways o’ killin’ a pig than cuttin’ ’is throat, and when I takes a contrac’ in ’and, I likes ter work it out shipshape.
1952		(con. 1920s) ‘Harry Grey’ Hoods (1953) 51: People came to us with what we called ‘contracts.’ [...] Contracts to murder their business partners, sweethearts, brothers, [etc.].
1970		G. Scott-Heron Vulture (1996) 95: If a man puts a contract on another man, he really signs one on the whole community.
1983		N. Heard House of Slammers 85: His contract on Junior Blake seemed to have garnered him even more adherents.
1992		G. Disher Paydirt [ebook] ‘There’s a fucking contract out on him’.
1998		J. O’Connor Salesman 327: Someone in the flats is after tellin’ her there’s a contract out on me.
2007		N. ‘Razor’ Smith Raiders 183: The fruitcakes, desperos and knuckle-draggers will fall over each other [...] to take the contract.
2010		L. Redhead Thrill City [ebook] They reckon he was hit over some sort of drug money — there was a contract out on him.

2. (US police) a corrupt agreement involving regular payments to the police.

1972		J. Mills Report to the Commissioner 170: [H]e made it sound like a contract, a politician’s kid or something like that.
1973		E.F. Droge Patolman 53: For the most part [payoffs] centered around gamblers who paid quite regularly, but they also included tow truck operators on accident scenes, city marshals on evictions, and other various ‘contracts’ or ‘scores’.
1996		(con. 1965) J. Lardner Crusader 63: The task of collecting the pad money was shared by the cops regularly assigned to the sector. [...] Boyd informed David that he would have to ‘honor all the contracts’ if he wanted a permanent seat.