A sentence can be rewritten to place the indirect object within a prepositional phrase. Indirect objects conserve words and increase precision. She gave a treat, hence it was the treat being acted being acted upon by the cat's owner. The cat was not a direct object of an action. An objective complement refers to a direct object.
Complements are usually nouns, pronouns, or adjectives.
In this case, a noun is acting as an adjective. Clause A clause is a part of a sentence that contains its own subject but is not a complete sentence. Phrase A group of words without a verb used as an adjective or adverb. Appositives An appositive explains or describes the noun or pronoun it follows. Appositives are set apart by commas.