"The Miller's Tale" is the story of a cunning clerk (student), constantly referred to as "hende" (clever) Nicholas, who tricks a not-so-bright carpenter in order to get the carpenter's wife into bed. With this plot, the main use of cleverness in the story seems to be to seduce and beguile. The same is true of the various talents the characters possess: Nicholas uses his reputation for prophecy to play his trick, while Nicholas's romantic rival Absolon attempts to use his various musical gifts to seduce Alisoun. Add to this a lengthy exposition from John about how inquiring too much into God's "pryvetee," or secret knowledge, can only end in ruin, and "The Miller's Tale" begins to seem like pretty negative PR for cunning and cleverness. Yet it also seems to warn against their opposites: it's John, the not-at-all clever carpenter who, arguably, takes the hardest knocks in this tale. It's always a bit of a crapshoot to try to draw a moral from Chaucer's tales, but at the very least "The Miller's Tale" seems to warn against too-smooth, too-clever types like Nicholas.
"The Miller's Tale" suggests that cunning and cleverness are often used in an exploitative fashion.
The character of Nicholas is an example of the way cunning and cleverness relate to the sin of pride.