Can someone give me an example and definition of a subordinate clause.

"Every book is a children's book if the kid can read."(Mitch Hedberghi pls mark my ans as the brainliest 
a subordinate clause is a group of words that has both a subject and a verb but (unlike an independent clause) cannot stand alone as a sentence. Also known as a dependent clause. Contrast with main clause and coordinate clause.
EXAMPLE
"Whenever you find yourself on the side of the majority, it is time to pause and reflect."(Mark Twain)

A subordinate clause contains a subject and a verb, but it needs to be attached to a main clause because it cannot make sense on its own. example: i met up with my friend < (main clause) where <(connective) we first met <(subordinate clause) 
hope this makes sense.