Answer:
Yes.
Step-by-step explanation:
This is a clause. It is called an independent clause because it depends on another part of a sentence. You can't simply say "All the people at the party" for evidently, that does not make sense. However, you could add a second part to the clause that would make it a sentence:
All the people at the party loved the music.
Without the rest of the sentence, the clause is simply a clause. Thus, it is a dependent clause.