Green’s Dictionary of Slang

to take on a job as a temporary worker, usu. a secretary.

1978		Times 2 Oct. III: Most of the students had given as their explanation for deciding to temp: ‘To gain office experience before taking up a permanent job.’.
1999		Meantime Manager May 66: One of the biggest benefits to temping is the freedom to change jobs if one doesn't work out.
2001		C. Stella Eddie’s World 10: I worked here about six months ago. Temping.
2024		J. Meades Empty Wigs (t/s) 381: [S]he was temping at the 19th hole! A barmaid!