A Clause! What the???

What is a clause?
an expression including a subject and predicate but not constituting a complete sentence

so what’s a subject?
one of the two main constituents of a sentence; the grammatical constituent about which something is predicated.

and what’s a predicate?
The predicate of a sentence is the part of the sentence that makes the assertion about the subject. The main part of the predicate is a finite verb (which must be present). The predicate can be a verb alone, or a verb and other words related to it.