Related Clues:

• MMXXI, e.g
• In Blackpool, say, where one can walk for miles?
• American high school dance
• 2021 is one
• One might be used as a four-digit PIN
• It's seen on Scotch bottles
• Last part of a date?
• Wine bottle indication
• Big night for seniors
• Long short time
• 'Will you go to ___ with me?' (senior's request)
• One-hundredth of a century
• Once around, so to speak
• "The ___" (2016 musical centered around a high school dance)
• YYYY on a form