Related Clues:

• No Derby contender
• Annoy repeatedly
• Decrepit horse
• Xanthippe, e.g.
• Don't bet on it
• Pester repeatedly
• Gadfly
• Broken-down horse
• Overworked horse
• Stay on one's case
• Complain, complain, complain
• Hector
• Complain chronically
• Jade
• Very old paint, e.g.