Clever often carries the sense, and I quote, “Good-natured, obliging. In Great Britain, a clever na is an able man who performs a deed well with skill or address.” In the north, you might hear a response to “How are you doing?” as “I am cleverly.” This would mean “I am in good spirits and doing well.”

I don’t think that Dr. Mohler is picking up the right Brittish meaning. THat doesn’t flow well with his thoughts. On the other hand, he may have heard the phrase, “He’s a clever clog” or a “clever Dick”. this carries a negative connotation. This means someone is behaving in a way that is a put on. Clever Dick or Clever clog means “an intellectual who is ostentatiously and irritatingly knowledgeable.” He is more show that substance.

One would need to ask Dr. Mohler what he meant, but it sounds like it is far from a compliment.
JJ