Possible Clues:

• Multi-disciplined contest
• Race suggested by 19-, 39- and 59-Across?
• Swimming, running and cycling
• Sporting event in North Italy cut short surprisingly
• 'Ironman' competition
• Perhaps halt intro for an athletic event
• Athletics event
• In the event, half of them will enter competition fixed for later?
• Most of the parts to test available for three races
• Ironman event comprised of the last words of 19-, 39- and 58-Across