Green’s Dictionary of Slang

smart, esp. when overly so.

2000		Guardian Rev. 4 Mar. 3: An apple-cheeked, spanky-clean-looking rookie.
c.2003		Dalton Vrij ‘Tying Off’ on Inter-zone.org 🌐 Sucks down the last of 16 oz apple juice, pops in a ciggie, spanky box of Winston 100s.