I already have a Tesco Bank Credit Card, can I apply for the Clubcard Plus Credit Card?

Yes. As long as you don't already have two Tesco Bank Credit Cards and/or haven't applied for one in the last month.
If you've previously been declined for a Tesco Bank Credit Card and want to apply again because your circumstances have changed, please leave at least 6 months from your last application.
UK residents. 18 and over only. Subject to status.