Possible Clues:

• Harm the reputation of
• 'Denigrate, slander (6)'
• To lie about another. To tell the truth about another
• Endlessly put off covering a mark and smear
• Charge falsely
• Give a bad rep to
• Do a hatchet job on pantomime character over engineering loud music
• Backbite
• Sling mud at fellow taking morning afloat in river
• Malign American woman taking in English female