There's also quite a few scheduling libraries for Clojure: (from simple to very advanced)
Straight from the examples of the github homepage of at-at:
(use 'overtone.at-at)
(def my-pool (mk-pool))
(let [schedule (every 1000 #(println "I am cool!") my-pool)]
(do stuff while schedule runs)
(stop schedule))
Use (every 1000 #(println "I am cool!") my-pool :fixed-delay true)
if you want a delay of a second between end of task and start of next, instead of between two starts.