Complex sentence: The station was once known as "Harringay Stadium", as there was a greyhound-racing track next to the station-this has now been redeveloped as the Sainsbury's supermarket.
Split into simpler sentences: The station was once known as "Harringay Stadium", as there was a greyhound-racing track next to the station. The stadium site has now been redeveloped as the Sainsbury's supermarket.