sly

Synonyms: arch artful astute bluffing cagey calculating canny captious conniving covert crafty crooked cunning deceitful deceptive delusive designing dishonest dishonorable dissembling doubledealing elusive foxy furtive guileful illusory impish ingenious insidious intriguing mean mischievous plotting roguish scheming secret sharp shifty shrewd slick smart smooth sneaking stealthy subtle traitorous treacherous tricky underhand unscrupulous wily

Antonyms: honest open simple straight straightforward unclever