Green’s Dictionary of Slang

peg n.5

[peg v.4 ]

(Aus./N.Z. und.) a look, a survey, thus keep the peg, too keep watch.

[Aus]Bulletin (Sydney) 26 Apr. 45: We give it a peg and decide to give the Limp another try.
[Aus]R.G. Barrett Real Thing 62: Norton had a peg out of the side of his eye.
[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 137/2: peg n. 1 a look, a stare 2 (also pegger) a lookout. [...] keep (the) peg to act as a lookout, to keep watch.