Wise to (2,2)
'wise to' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for in on that I've seen before include "Wise to" , "Aware of secret" , "Privy to" , "Participating in - knowing about" , "Sharing with" .)
(Another definition for inon that I've seen is " Privy to".)