Green’s Dictionary of Slang

to lead a regular, routine (working) life.

1962		R. Cook Crust on its Uppers 25: Better than nine-to-fiving it, sex, cocktails and rows in a pseudo-tudo cottage.
1971		R. Woodley Dealer 117: ‘Jimmy always aspired to be a hustler,’ a friend said. ‘Even when he was nine-to-fiving’.
2016		A. Wheatle Crongton Knights 187: He looked like someone who nine-to-fived at a bank.