One and a very quick way:
(flatten (vec {"red" "blue"}))
=> ("red" "blue")
If you really want an array:
(into-array (flatten (vec {"red" "blue"})))
=> #<String[] [Ljava.lang.String;@4dc2753>
Keep in mind that in Clojure, ["red" "blue"] is a vector, not an array. And { } means map. Clojure first creates an array map but later, it promotes it to hash map when it is necessary.