Rewrite apply function to use recursion instead
Lisp is a multiparadigm language.

apply is just as lispy as recursion, and, in a way, much more so (think in HOFs)!

Style


Please fix indentation.
Please write #'foo instead of (function foo).


Implementations

The first (HOF) version can be much more efficiently rewritten in using mapcan (provided defscribe-path returns fresh lists):

(defun describe-paths (location edges)
  (mapcan #'describe-path
          (cdr (assoc location edges)))))


The second (recursive) version can be made tail recursive using an accumulator. This would help some compilers produce better code.

(defun describe-paths-recursive (location edges)
  (labels ((processx-edge (edge acc)
             (if (null edge)
                 acc
                 (processx-edge (rest edge) 
                                (revappend acc (describe-path (first edge)))))))
    (nreverse (processx-edge (cdr (assoc location edges))))))


Note the use of revappend/nreverse instead of append to avoid quadraticity.