The following snippet, featuring the "fantasy function" clone-function, illustrates what I'd like to do:

(defvar last-enabled-foo nil)

;; hold on to a "clone"/copy of third-party function enable-foo
(defvar original-enable-foo (clone-function 'enable-foo))

;; replace enable-foo with a wrapper function around it
;; module foo.el
(defun enable-foo (foo)
  (setq last-enabled-foo foo)
  (funcall original-enable-foo foo))

Basically, clone-function ensures that original-enable-foo refers to a function that is completely distinct from the newly defined enable-foo.

How could one implement clone-function?