Green’s Dictionary of Slang

(Aus./UK) a brawl.

1895		Mirror of Life 11 May 6/3: [S]ome of the Fancy [...] went round to the Blue Anchor to administer toko to the host; but [...] when they played the game of ‘all-in’ the scrapper often left the house a sadder if a wiser man.
1986		R.G. Barrett Real Thing 112: A bit of an all-in started and George king-hit Les.
1991		R.G. Barrett Between the Devlin 62: ‘It finished up an all-in with the bouncers’.