Definition of a new one in English:

a new one

phrase

informal
  • An account, idea, or joke not previously encountered by someone.

    ‘somebody being too lazy to talk—that's a new one on me’
    • ‘Dealing with complaints when I'm not even clocked in is a new one even for me!’
    • ‘That's a new one on us, a new one that we hope goes straight out of fashion.’