as cunning as a fox字面意思像狐狸一样狡猾，引申为非常狡猾。

【例句】
Be careful with that guy, he’s as cunning as a fox.
小心那个人，他非常狡猾。

Be careful in your dealings with Sammy; he's as cunning as a fox and will try to take advantage of you.
你同萨米打交道要小心，他非常狡猾会设法利用你的。