This is an interesting question. It is a special case.
1. "He played clarinet" - in the past, he was able to play (and did play) one or more clarinets. He was able to play that type of instrument. This refers to clarinets in general. 2. "He played a clarinet" - in the past, he played an actual clarinet. 3. "He played the clarinet" - means the same as 1. 4. "He played the clari