The homoiconicity of Lisp is not what gives it this superpower. It is rather Lisp's dynamic nature that actually allows you to keep running your project while also developing it that is crucial - something that Clojure running on the JVM can actually only approximate.

For example, in a full CL, you can modify a class that is currently being used, and objects of that class will adjust accordingly (for most modifications). This is not possible for the JVM - to modify a class, you would have to unload it, which can only happen if the Class object is garbage collected, which requires all instances of the class to be GCd, and the ClassLoader that loaded that class as well - only then could you add a field with a default value to the class.