Possible Clues:

• Track meet infractions ... or short words hiding at the beginning of the answers to starred clues
• Race errors, and what 17-, 27- and 46-Across have
• Swimming infractions, and what the first words of the answers to starred clues can all have
• Sprinters' fouls
• Reasons to begin a race over … and a hint to 17-, 25-, 39- and 49-Across
• What 17-Across, 11 and 35-Down all have in common