Who Could This Be Rebus #241

If you're new to Rebuses, you can read how to solve a Rebus here (link opens in a new window).

Do you need a little help? Click to reveal a clue to the above Rebus.
Here is clue to help decipher the hidden meaning. Said about someone who is really good at a subject in education.
Do you think you have got it? Click to view the answer.
You can only see the “top” of the word “Class”, to give the answer: Top Of The Class