Green’s Dictionary of Slang

clag n.

[northern dial. clag, a sticky mass]

(Aus. prison) porridge.

1990
Show quotations
[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Clag. Porridge.

In phrases

clagged out (adj.)

(Aus.) exhausted.

2016
Show quotations
[Aus]N. Cummins Adventures of the Honey Badger [ebook] VITAL AUSSIE VERNACULAR Tired: 1. Buggered 2. Shagged 3. Had the sword 4. Rooted 5. Clagged out 6. Done and dusted.