Related Clues:

• It's underfoot!
• Cod's neighbor in the showcase
• Part of many titles
• Many a title starter
• ''O --- Mio''
• Cod's showcase neighbor, perhaps
• Unpartnered
• Unfrequented
• Seafood choice
• Flying solo
• Pump part
• See 116-Down
• Word alphabetizers ignore
• With 36-Across, rhinologist's study
• 'The Princess Bride' topic