btw, your question assumes that Common Lisp is not evolving. This is not correct at all.
Which improvements Clojure evolving consists of? 
Transducers? Cl got them too: <a href="https:&#x2F;&#x2F;github.com&#x2F;aamedina&#x2F;transducers" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;aamedina&#x2F;transducers</a>
Transactional memory? <a href="http:&#x2F;&#x2F;stmx.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;stmx.org&#x2F;</a>
ClojureScript? <a href="http:&#x2F;&#x2F;davazp.net&#x2F;jscl&#x2F;jscl.html" rel="nofollow">http:&#x2F;&#x2F;davazp.net&#x2F;jscl&#x2F;jscl.html</a><p>These are only infrastructure things, Common Lisp has language features which are just impossible in Clojure while it based on JVM.