Green’s Dictionary of Slang

(Aus.) to understand.

1999		G. Seal Lingo 92: To violet crumble is to tumble, as in to understand something: oh, now I violet crumble! derived from the name Violet Crumble bar, an Australian confectionery of chocolate-coated honeycomb.
2002		Pete’s Aussie Sl. Home Page 🌐 violet crumble: tumble, take a tumble, to understand .