In what way? The Common Lisp standard hasn't changed since 1994.
> essential features like multithreading are not standardized
No one has made up their minds what the best atomic test-and-set operations are. A lot of platforms can't even agree on semaphores vs. condition variables. Which concurrency primitives do you think should be standardized, and which should be left to libraries? To me that seems like a trick question, because there's no good answer.
For example, I think software transactional memory is a dead-end, and shouldn't be part of a language standard, but many people involved in Clojure obviously disagree.
> More importantly, it doesn't have a focus on immutability and functional programming by default.
You can always do FP in Common Lisp, but you can't do gotos in Clojure.
