What is a clause?

A clause, simply put, is a part of a sentence. We’ll give three examples.

Johnny is a doctor.

This is a sentence that doesn’t have any clauses.

Johnny is a doctor, even though you would never know this if you met him socially.

This is one sentence that has two clauses.

Johnny, who I play baseball with on Fridays, works at the hospital.

This is another sentence with two clauses. ‘Johnny’ can’t be considered a clause, because a clause (or a sentence) always needs to have a subject and a verb.