Related Clues:

• 'Who knew?'
• Any chess piece (even the queen!)
• 'That's impressive!'
• Any chess piece
• Haw alternative
• Dog's best friend?
• Naive utterance
• 'That's unbelievable!'
• It can follow the first parts of 20-, 38- and 54-Across to form names of comics heroes
• One overboard?
• "Who'da thunk it!"
• Shout of surprise
• Beaver Cleaver interjection
• "Hoochie Coochie ___"
• Neil Diamond is a "Solitary" one