Related Clues:

• Old gray mare, say
• Carp, carp, carp
• Shrew
• Persistent critic
• Pester
• Termagant
• Torment
• Detractor
• Bettor's interest
• Back seat driver, e.g.
• Complain, complain
• Remind too often
• Pick on
• Over-the-hill mount
• Equine loser