Green’s Dictionary of Slang

slave v.

to work.

1892		H. Lawson ‘Jones’s Alley’ in Roderick (1972) 39: I got tired of slavin’ there for next to nothing.
1914		Joyce ‘The Dead’ Dubliners (1956) 192: I think it’s not at all honourable for the Pope to turn out the women out of the choirs that have slaved there all their lives and put little whipper-snappers of boys over their heads.
1928		M.C. Sharpe Chicago May (1929) 239: This did not discourage me. I slaved on.
1936		D. Stivens Tramp and Other Stories 51: A bloody poor Christmas Eve, he was thinking, on my own . . . after slavin’ my guts out on the farm.
1941		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 1 Mar. 9/7: Viola Jones claims that her Louis Roach slips out with Justine Roney while she herself is ‘slaving’.
1959		A. Sillitoe ‘The Disgrace of Jim Scarfedale’ Loneliness of the Long-Distance Runner (1960) 122: Think of all the times she’d slaved for him.
1968		‘Sl. of Watts’ in Current Sl. III:2.
2000		P. Beatty Tuff 33: You know that tan building right next to it? I used to slave there. Strudder, Farragut, and Peabody.

In derivatives

slaver (n.)

(US black) a worker.

1943

D. Burley N.Y. Amsterdam News 23 Oct. 21: We never stashed on the turf to brace some slaver in our hookers.