Green’s Dictionary of Slang

stylish, fashionable, well cut; also adv.

1840		Courier (Hobart, Tas.) 27 Oct. 3/1: [advert, from UK source] [A] pair of long sleeve moleskins, built hanky spanky, with a double fakement down the sides.
1857		advert in ‘Ducange Anglicus’ Vulgar Tongue 45: Pair of Moleskin, all colors, built hanky-spanky, with double fakement down the side, and artful buttons at bottom, half a monarch.
1895		Mirror of Life 2 Feb. 11/1: Gus Leach advised Jem Mace, Burge, Nickless, and the introdoocer to come round to the hall in a hanky-panky barouche and rattling pair of greys.
1913		E.L. Warnock ‘Terms of Approbation And Eulogy’ in DN IV:i 24: hanky-spanky. Dashing, stylish, nobby; specifically of well-cut clothes [...] ‘He’s some hanky-spanky fellow that’s been hanging round her for quite a spell.’.