Is the group of words in bold a phrase or a clause

The support beams beneath the abandoned jetty

Phrase

Before answering the question let us analize what a phrase and a clause are? a clause is a sentence that contains a subject and a predicate. Every sentence must have at least one main clause. A main clause contains an independent subject and a verbal structure and expresses a complete thought.

There are two different kinds of clauses: first,"Dependent" clauses are sentences that cannot stand alone and do not convey full meaning, for example: "When I go rock climbing" this sentence has a subject and a verb, but its meaning raises questions, it does not have a complete idea of its own. Second "Independent" clauses are sentences that can stand alone as a full sentence and convey a full meaning, for example: "I prefer climbing in landscapes that present a challenge."

A phrase is a group of words that can lack either the subject or the verb and cannot stand alone and do not convey full meaning because it lacks one of the two that are essential in a sentence, for example: "going places", "my brother in a good mood"

The main and most important difference between a clause and a phrase is that a clause if it is independent is considered a full sentence, whereas a phrase could never be considered one.

The group of words:

"The support beams beneath the abandoned jetty."

Is a Phrase for it lacks a predicate