Possible Clues:

• Adolescent as a born troublemaker originally, growing up
• Adolescent's eaten crackers by case in glee
• From 13 to 19 years old
• Support old horse, note, quite young
• Stand and scold over end of immature adolescent
• Adoles-cent
• Like many Olympic gymnasts
• Support horse close to race, not yet fully formed?
• Like Mutant Ninja Turtles
• Like adolescents