Related Clues:

• Lay out in steps
• Quite strange
• Unpaired
• Missing a few marbles
• Map
• Kind of duck
• 'O ___ babbino caro' (Puccini aria)
• Preserved, in a way
• In a state of abeyance
• Like all primes but one
• Lacking a match
• Architect's offering
• Guaranteed to succeed
• Atypical
• Quite unusual