Green’s Dictionary of Slang

(Aus.) to beat up, to knock down.

1986		R.G. Barrett Real Thing 47: Norton shortened the big Wests forward up, but the referee thought it was Fred and sent him off.
1998		R.G. Barrett Mud Crab Boogie (2013) [ebook] She knew what she was doing and if Billy had just been some mug he probably would have got shortened up.
2004		R.G. Barrett Rosa Marie’s Baby (2013) [ebook] ‘I want hom shortened up [...] There’ll be a drink in it for you’.