He's as sly as a fox.

他很狡诈。

youdao

Before I could say anything further, the principal gave me a sly, almost sarcastic smile.

我还没来得及说什么，校长露出了一个狡猾、几乎有些讥讽的微笑。

youdao

He said nothing but gave me a sly grin that made me feel terribly uneasy.

他什么也没说，只朝我狡黠地咧嘴一笑，令我感到极为不安。

《柯林斯英汉双解大词典》

As the accidental titan of American destiny, Walter Huston dominates the film with a sly yet grand manner and a prophetic diction.

NEWYORKER: Abraham Lincoln

It's a sly, ironic portrait of a Goethe-quoting 60-something gent who is dating a considerably younger woman, much to the sardonic amusement of her friends.

WSJ: How to Be an Aging Rocker | Sightings by Terry Teachout

The trick was to send out clippings so sly that a tired editor might not notice that they were written by an advertising outfit.

NEWYORKER: The Lie Factory