Possible Clues:

• Mary Poppins pal
• Ernie's bud
• One of a "Sesame Street" duo
• Lion player Lahr
• 'Sesame Street' character with a unibrow
• 'Sesame Street' roomie
• U.K. singer Jansch
• Puppet whose shadow is at the start of 43-Across
• Half a PBS pair
• Kids’ TV character with a thick unibrow