Answer:
Makes up a whole sentence basically, so isn't a phrase, but a sentence.
Step-by-step explanation:
You need your subject and predicate to make a clause or else it isn't a clause. A person or thing doing something.
For example:
Correct - He yells... when he is running. (clause). He's not yelling until he's runs . So in this case, running is the predicate and he is your verb. He's not yelling all the time, he only yells when he's running. He's running so he's yelling.
Incorrect: He yells... all the time. There is no verb and he isn't doing anything.
Just always have a subject and predicate when forming a clause. I don't know if this is enough for you, apologies.