Green’s Dictionary of Slang

to act as a hired thug.

1714		T. Lucas Lives of the Gamesters (1930) 225: His brethren in iniquity, from whom he also had a pension, for being [...] ready to fight, or rather bully for ’em.
1734		Ipswich Jrnl 25 May 3/1: He had for some time liv’d wholly by Gaming, Pimping and Bullying for the Women of the Town.
1865		H. Kingsley Hillyars and Burtons (1870) 64: Pistol, the cutpurse, ruffling and bullying it.