Do you need to know Java to code in Clojure
In general: no.
But because Clojure is built on the JVM, you will sooner or later meet an situation where you want to do something where there is a Java Library you can use, but no Clojure library. In these situations you need to use what is called the Java Interop. The code doesn’t look like Java, but it is useful to know enough Java to take an existing example and re-write it into Clojure.