Possible Clues:

• + or -, to mathematicians
• One who gives talks about parking next to European driver
• One receiving many calls at work
• Glyndebourne company's trip putting off posh conductor?
• Old phone company worker
• 'Smooth ___' (Sade hit)
• Driver for pointless proportionate representation
• Artwork flipping rubbish, which may be a minus
• Person using drill interrupts speaker
• Person running business peeled waterproof off