* "Cleverest" is the superlative form of "clever," meaning the most clever among a group. You'd use it if you are comparing more than two things or people.
* "Most clever" is also correct, but it emphasizes the degree of cleverness. You'd use it if you are emphasizing the level of cleverness, even if you aren't directly comparing to others.
Here are some examples:
Cleverest:
* "She was the cleverest student in her class." (comparing her to other students)
* "This is the cleverest solution I've ever seen." (comparing it to other solutions)
Most clever:
* "That was a most clever move." (emphasizing the degree of cleverness)
* "He is a most clever strategist." (emphasizing his cleverness)
Ultimately, both options are grammatically correct. Choose the one that best fits the context and your intended meaning.