Possible Clues:

• Haughty attitude
• Over 20 hands up there behaving arrogantly?
• The arrogance of many hands?
• Pegasus?
• Perhaps that's what 17 down makes one so disdainful to be on
• Many hands?
• 6 down makes no pony about this?
• What many hands make one aloof on this
• The worse for drink and a drug on which one is over-assertive
• What 1 across may make