Related Clues:

• "Let me know," on invites
• Send one's regrets, say
• "Answer this invitation please" (Abbr.)
• Say maybe, maybe
• 'Let me know if you're coming'
• Invitation stipulation, briefly
• Get back to a host, say
• "Please reply," in brief
• Agree to go, say
• "Answer, the invitation, please" letters
• ''We won't be bartending''
• Request to a prospective guest
• "Will you be at my 23-Across?" (Abbr.)
• Republican's second in command, please reply
• It might mention a plus-one