Clojure (and ClojureScript via Reagent[1]) is what got me into functional programming in the first place. However, as a developer working in a .NET shop I found more opportunities (e.g. .NET interop) to do "functional programming" in F#, which has also been well support cross-platform for some time.
At the time, Leiningen was still in its infancy and I hit a lot of issues getting things running but when I finally did the language had a profound impact on me as a developer.