Possible Clues:

• "You will __ the day!"
• Wish you could take back
• A way for France to show regret
• Word on Parisian street signs
• Herb might regret this
• Poe's 'The Murders in the ___ Morgue'
• Regret royally
• Want to undo
• Herb of sorrow?
• Sport at Twickers English regret