Googling a little bit: Common Lisp as an Extension language
But keep in mind that Common Lisp wasn't designed from the ground up to be an extension language, unlike Lua or Guile.
A general advice: try to use an extension language that really makes the work of writing them easier, and remember that mastering Lisp so you can be really productive with it can take quite long (and there are not many people around that can stand so many parens xD).
