Green’s Dictionary of Slang

bustler n.

(Aus.) a notably hard worker in a shearing shed.

[Aus]Bulletin (Sydney) 8 Dec. 14/2: And, anyhow, if ‘Werrimee’ is a ‘bustler’ or a ‘tiger,’ a paddockful of State Frights in full cry wouldn’t keep him awake after a day’s shearing.