Possible Clues:

• Nat and Natalie
• "Unforgettable" singers
• Kenneth and Ashley
• Natalie and Nat King
• 'Unforgettable' singers
• Hardy cabbages
• Jazz drummer Cozy and a king
• Duo that had a hit with 'Unforgettable'
• Neil, vintage golfer
• Neil, first golfer to win a professional event in six different decades