Related Clues:

• Subject of many a 59-Down photo
• Onager, e.g.
• One may be kicked for motivation
• Paragon of stubbornness
• Equine animal
• Mule's parent
• Pumpkinhead
• "With the jawbone of an ___ ..." (Judges 15:16)
• Bungling fool
• One in a pack
• Hinny’s mother
• It may be packed down
• Balloonhead
• Intractable beast
• Wild donkey