Green’s Dictionary of Slang

(N.Z.) smart, fashionable.

1943		J.A.W. Bennett ‘English as it is Spoken in N.Z.’ in AS XVIII:2 Apr. 89: Tonky suggests superior social standing or ‘tone.’.
1988		McGill Dict. of Kiwi Sl. 114: tonky, fashionable [...] eg ‘My, my, doesn’t she look tonky.’.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].