A subordinate clause—also called a dependent clause—will begin with a subordinate conjunction or a relative pronoun and will contain both a subject and a verb. This combination of words will not form a complete sentence. It will instead make a reader want additional information to finish the thought. (From a grammar website).
Are there any instances which contradict a dependent clause beginning with a subordinate conjunction or relative pronoun as written above.
He arrived late for work again, not that it mattered. (for example).