We have used clj-ml[0], which wraps a bunch of Weka stuff, as well as the XGBoost JVM bindings. I've used Bayadera[1] and Dragan's other tools for linear algebra, although not in production. I was always sad that Incanter didn't really go anywhere, but at this point I wouldn't be surprised if Clojure became a respectable platform for data science, especially given Clojurists Together's funding focus this quarter[2].
0: https://github.com/shark8me/clj-ml
1: https://github.com/uncomplicate/bayadera
2: https://www.clojuriststogether.org/news/q4-2019-funding-anno...