Related Clues:

• Request from a party leader
• Invitation inscription
• ''Let us know if you're coming''
• Say whether you'll come
• "Please answer"
• Accept or decline
• Inform the host
• Part of a prospective bride's pile
• Say you'll go, say
• See 20 Across
• Letters on an invite
• It may involve regrets
• Letters before a phone no., perhaps
• Promise attendance, briefly
• Don't just show up