Related Clues:

• Gripe over and over
• Gripe repeatedly
• Annoy no end
• Really bug
• Whiner
• Bag o' bones
• Equine has-been
• Bother repeatedly
• Run-down horse
• Be petty
• Unlikely race winner
• Old chestnut?
• Bettor's interest, perhaps
• Racehorse, slangily
• When said three times, comment of annoyance