I'll be honest i haven't listened to a lot of the clash, just a handful of the famous ones. They sounded like they had a few different influences and styles over what i associate (rightly or wrongly) as the punk sound i dislike. Just take their 2 biggest mainstream hits, probably London calling and Rock the casbah. That isn't how i think of punk music. I'm not a musician, i just know that every time i have been to a punk nignt at a club or a cd was put on i never enjoyed it. One of mates went through a punk stage so i endured it as infrequently as possible.