What's made clojure so great, imo, is its unicorn status as a principled-yet-practical language. That "principled" part is not worthless---it means that a lot of great minds are drawn to it. Before react took over the world, clojure folks were already taking steps in that direction.
A lot of other things. The "sequence" as a core abstraction is very powerful. Immutable data structures by default make functional programming perfomant and efficient.
Speaking of data structures, data structure literals have spoiled me for other languages. After Java, especially.
And none of this mentions clojure's lispiness. The ease of metaprogramming has allowed the community to build some of the best tooling out there, between CIDER for emacs, and Figwheel for the browser---oh, did I forget to mention clojurescript? Being able to reuse code on the front and backend is great for web applications.
Clojure isn't "everything." I think I'd still benefit from learning Haskell, APL, and Forth, and I wouldn't mind knowing Ruby and js a bit better. And I'll probably be dragged back to Python and R if I keep doing maths.
But if someone asked me which single language would probably do the most for them professionally, I'd say clojure. It's the language people start startups so they can use it.