Possible Clues:

• Marathon volunteer aide
• Expert in image-making maybe who walks nervously up and down?
• Indiana pro basketballer
• Kind of fitness test for K-12 students
• Type of horse; caper (anag.)
• One in pair who sets rate of travel
• Prince keeping superb racing horse
• The NBA's Reggie Miller, e.g
• Gainbridge Fieldhouse player
• Runner in the lead