Complex sentence: The Carter Handicap is a race for thoroughbred horses, three-year-old and upwards, run at a distance of 7 furlongs at Aqueduct Racetrack.
Split into simpler sentences: The Carter Handicap is a race for thoroughbred horses three-year-old and upwards. The race is at a distance of 7 furlongs at Aqueduct Racetrack.