Dear Experts, I am sorry to point off that in the study material of English grammar in the topic Adjectives the comparative and superlative form of adjective clever is given cleverer and cleverest respectively while in of my questions when i asked the same thing to you, you told me that more clever and most clever is correct. So, please clarify.
Dear student, it is one of those exceptional adjectives, which can take both forms. However, the more preferred one is 'clever; more clever; most clever'. More example of such adjectives are simple, humble, gentle, common, polite, etc.