Do you spell it clearer or more clear?

Comparatives in English are all replacements for the standard "more". There are very few occasions when a descriptive adjective cannot use the "more" form (one of which is when you are already using a comparative, i.e. something can't be "more smaller"). However, more common in usage is to use the -er form, "clearer". Of course, when modifying a verb, the adverb form must be used ,"more clearly". "Can I make the meaning clearer?" = "Can I make the meaning more clear?"