See: https://twitter.com/alandipert/status/329828365882249217

gistfile1.clj

(defn remove-first [pred coll]
  (let [[xs ys] (split-with (complement pred) coll)]
    (concat xs (rest ys))))

(remove-first (partial = 3) [1 2 3 1 2 3])
;;; (1 2 1 2 3)
 
(remove-first even? [1 2 3 1 2 3])
;;; (1 3 1 2 3)