Green’s Dictionary of Slang

1. to work as a prostitute.

1959

F. Norman Fings II i: And tho my Lil is quite prepared to go outside and earn.

2. of a police officer, to take bribes.

1974

G.F. Newman You Flash Bastard 12: Some almost certainly making deals with suspects, possibly either to entrap them or earn from them.

3. to make a dishonest profit from a crime.

[1849		Paul Pry 22 Jan. n.p.: [S]ome mustachioed sharper [...] who will jocularly pronounce upon his ‘infernal run’ of ill-luck; while at the same time he courteously buttons up his breeches-pocket upon the three or four sovereigns he has ‘earned’].
1977		D. Powis Signs of Crime 182: Earn To make a corrupt or dishonest profit. A thief might say about a proposed fraud or illegal scheme: ‘We can all really earn on this one!’.
1989		J. Morton Lowspeak.
1992		in R. Graef Living Dangerously 90: I want to learn a trade [...] So I won’t have to go out ‘earning’.
2005		Guardian Society 13 July 🌐 Basically any dickhead could come and earn, could come and sell drugs.