I am suggesting this is Chlenias zonaea because it has a quite prominent white patch at the base of the forewing with a black mark alongside it as clearly shown on the supporting CD page 2/4 for that species for Part 5 Moths of Victoria. The general wing patterning seems also to match photos of male specimens in Moths of Victoria and on the supporting CD. Bold Systems 4 confirms that this species also occurs in SE NSW as well as Victoria and several of the male specimens photographed there seem to be a good match also.
Chlenias banksiaria, auctaria, nodosus and zonea are very difficult to tell apart, even with a bunch of specimens in the hand. I think Chlenias banksiaria grp is the safest identification. ANIC has far fewer specimens of zonea than banksiaria, and they are from west of the ACT. Note that MoV says the Vic museum has only 13 zonea specimens, and they needed to examine genitalia to be sure of one zonea photo.