Green’s Dictionary of Slang

(N.Z. prison) a hiding place.

1982		G. Newbold Big Huey 85: Every smoko time, at about 20, Junk or Baine would pull their bombs out of snooker and brew up a cup of tea or cocoa. [Ibid.] 148: He had a secret compartment in his slot where he hid all his goods and [...] a couple of screws swooped on Ralph’s place and sprung his snooker.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 54/2: deep snooker (also heavy snooker) n. a very good hiding place [...] 171/2: snooker n. a hiding place.