Clojure and Scheme are very different languages in the Lisp family.
I see Kawa as an option if you need JVM, and you know you want Scheme.
From another direction: If the situation is that you have to be heavily integrated into a Java environment (at the library/linking level, not microservices, etc.), such as due to enterprise legacy systems, tech policy, or maybe an embedded system... but you'd get big wins by using a non-Java language with that... then I suppose your options might include Clojure, Scala, and maybe Kawa. (Maybe other options right now; one would have to look into it.)
I'd argue not. They're in the same family of languages, but Schema and Clojure feel offer very different programming experiences. Neither is really better or worse than the other, they're just different.
Personally, I would probably pick Clojure as a primary implementation language because it's big and enterprisey and heavyweight and has all the tools and whatnot that come with that. And I would be more inclined to pick Kawa for high-level scripting, DSLs, and suchlike, for the same reason.
If you have Scheme code that you, for some reason, want to run on top of Java (or the JVM), then Kawa is still relevant. Clojure is similar to Scheme (in some ways, but mostly by virtue of also being in the Lisp family and being a Lisp-1), but is not the same, compatibility with Scheme code was not the intent.
