Possible Clues:

• Write back as requested
• Click 'Going' on a Facebook event, e.g
• ___ card, part of a wedding invitation
• Say yes or no, say
• Say 'Sorry, can't make it,' e.g
• Request made in French initials
• Common abbr. from the French
• Republican's second in command, please reply
• Say you'll attend, say
• 'Let us know if you're coming' letters