What is a group of related words with a subject and predicate that acts to modify a verb adjective or adverb?

A group of related Words with a subject and predicate that modifies a verb, adjective, or adverb is called a "clause." Specifically, an adverbial clause serves this function by providing additional information about the manner, time, place, reason, or condition of the action described in the main clause. For example, in the sentence "She sings beautifully when she is happy," the clause "when she is happy" modifies the verb "sings."