Green’s Dictionary of Slang

(Aus./US black/drugs) one pound weight of marijuana.

1992		R.G. Barratt ‘Law is a Dope’ in What Do You Reckon (1997) [ebook] He got busted in Japan with half an elbow.
2000		South Park Mexican ‘Child of the Ghetto’ 🎵 Know how to slang me an elbow.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 65/1: elbow n. a pound of marijuana.
2007		Twista ‘Hustla’ 🎵 Used to be able to get the elbow for the six.