what is a clause
Clauses are units of grammar that contain at least one predicate (verb) and a subject. A clause, therefore, contains a single verb group. A clause is different than a phrase. A clause is a group of words with a verb and a subject.
Instances of the same can be seen in italics in the following sentences:
He has a chain which is made of gold.
The train had left by the time they reached.
I belong to a family which has fifteen members.
Types of clauses: