wily
WYE-leeadjMeaning clever at tricking others; crafty
Memory hook WHILE the dog sleeps.... While the guard dog snores, the fox tiptoes off with an egg; he plans his tricks for just that moment, because he is wily.
The wily fox waited until the farmer fell asleep, then slipped under the fence.
In context The chess champion was wily: she pretended to make a careless move, then sprang a trap that won the game three turns later.
Similar crafty, cunning, sly, shrewd
Opposite naive, guileless, artless
From wile, an old word for a sly trick.