Green’s Dictionary of Slang

(Aus.) the division of spoils or winnings.

1925		Riverine Grazier (Hay, NSW) 31 Mar. 2/6: McCracken, who was in good form, was also in the ‘chop up’ of the only sweepstake that took place.
1930		Morn. Bulletin (Rockhampton), Qld 20 June 8/2: One of the prettiest sights for many a day was the ‘chop-up’ [...] Four of the visiting punters sat round and in the centre was a pile of notes the amount of which could only be guessed. It was ‘two for you, and two for me’ and they were ten’s and five’s at that.
1932		Truth (Sydney) 18 Sept. 5/4: There are four of these boys, but one [...] does not figure as joint-owner. Still i [...] he is always in the chop-up, for the Smith brothers are shackled together [...] and what one does is good enough for the other three.
1983		Bulletin (Sydney) 1 Mar. 28/3: [O]ne of Sydney’s leading sportswriters collected £30 after the fights every Monday night at Sydney Stadium. It was his share of the chop-up [...] for publicising the combatants.