Green’s Dictionary of Slang

1. (orig. Aus.) someone who is usu. having financial problems, a poor person.

[1586		G. Whetstone Mirrour for Magestrates of Citties (2nd edn) H3: Then seazeth the third of these Cheaters upon this needie Gentleman, which is: The Broaker: who is (either) an olde Banckrupt Citizen; or some smoothe [...] Gentleman, farre in debte [...] bownde with hym for a C, pounds, shaarynge the Money betweene them].
1881		Bulletin (Sydney) 29 Jan. 5/1: The months ran out – so did the money; – and in the end ‘Dolly’ being to all intents and purposes a ‘broker;’ having, in short, nothing but his wardrobe, […] he sailed for the old country.
1890		P. Melon ‘Jack and Jim’ Sporting Times 4 Jan. 3: Get this fact into your nob, / You’re a broker ‘on your uppers,’ I’m a broker ‘on the job’.
1894		Truth (Sydney) 4 Nov. 5/3: I’m a ‘broker’and an outcast.
1897		Marshall Pomes 120: On his right a stoney-broke-er / In bad financial health [F&H].
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 29: BROKER: a man without money: simply broke, would perhaps mean that for time being he was without money on him: dead broke that he was without money at all. Dead motherless broke would mean without a chance of getting any money. Stonybroke seems to be a compound of hard-up and broke, stony being comparative of hard.
1938		D. Runyon ‘A Very Honorable Guy’ in Runyon on Broadway (1954) 413: There is no percentage in hanging around broker.
a.1946		‘The Open Book’ in G. Logsdon Whorehouse Bells Were Ringing (1995) 115: Now there’s boosters from poor Oklahoma, / And there’s brokers from old Arkansaw.
1977		(con. 1960s) D. Goines Black Gangster (1991) 232: The truck drivers are mostly brokers.

2. (drugs) a heavy drug user [they ‘go for broke’].

2001

ONDCP Street Terms 4: Broker — [...] heavy drug user.