Green’s Dictionary of Slang

not up adj.

[abbr. not up to standard]

(Aus.) second-rate.

[Aus]Bulletin (Sydney) 5 Oct. 32/1: [I] begged him to read it and compare it with some of the English work. He read it, and was ‘sorry to say it was “not up”’.
[Aus]Baker Popular Dict. Aus. Sl. (2nd edn).