Rich Hickey’s (He’s the designer of Clojure) comment on that is the 1st reference link on wiki:
Did you pick the name based on starting with the word “closure” and
replacing the “s” with “j” for Java?
It seems pretty likely, but it would
be nice to have that confirmed.The name was chosen to be unique. I
wanted to involve c (c#), l (lisp)
and j (java). Once I came up with
Clojure, given the pun on closure, the
available domains and vast emptiness
of the googlespace, it was an easy
decision.
http://groups.google.com/group/clojure/msg/766b75baa7987850