Complex sentence: The song for which they are mainly remembered, "Turning Japanese", was produced by The Jam's producer Vic Coppersmith-Heaven and reached the top three in the UK at the same time that "Going Underground" was at number one.
Split into simpler sentences: The song for which the group is best remembered, "Turning Japanese", was produced by The Jam's producer Vic Coppersmith-Heaven. It reached the top three in the UK at the same time that "Going Underground" was at number one.