A clause is defined as a group of related words that contains a subject and predicate (verb) and a phrase is defined as a group of related words that does not contain the subject and the predicate.
Let us take an example.
He was laughing at the joker.
Here, in this Sentence the Clause is at the joker as he was laughing as the predicate verb 'was laughing' and the subject 'he' is present and 'at the joker' is the phrase as it does not contain the subject and the predicate verb.