Green’s Dictionary of Slang

loose n.

1. (Aus.) an evening party.

1871

Hamilton Spectator (Vic.) 7 Jan. 1/7: If asked to an evening party, it is a ‘loose’, a ‘blowout’.

2. spare change.

1896

Mirror of Life 11 Nov. 3/1: [T]he bag-bearers in waiting the repository might have buzzed round him for all his loose.

SE in slang uses

In phrases

make a loose (v.)

to make one’s escape.

1709

N. Ward Secret Hist. of Clubs 165: A Lawyer’s Clark, who had venturd to make a Loose from the Finger Drudgery of Pen Ink and Paper, would usher in the Buxom Daughter.