The Bishop of Rome is the Pope. Among experts, there’s no disagreement as to whether Clement was the Bishop of Rome.
Perhaps you disagree that the Bishop of Rome holds a sort of distinction above other Bishops, but the fact that the Pope is a specific title for the Bishop in Rome supports the fact that calling Clement a Pope is not erroneous.
Perhaps you disagree that the Bishop of Rome holds a sort of distinction above other Bishops, but the fact that the Pope is a specific title for the Bishop in Rome supports the fact that calling Clement a Pope is not erroneous.