I’d use these three in the following way:

Clever I’d use to describe somebody who can think in innovative ways, usually to solve some sort of problem. A person who is uneducated or of low education can be as clever as a person of high education.

Intelligent I use to describe somebody who is highly educated or knows a lot of things.

Smart I’d use for somebody who knows a lot of things too, but knows how to use this knowledge to his advantage.