delivery level 2 discards functions that are used only inside eva l

I have a function

(defun foo (x)
 ...)

which is not used anywhere in the code.
Suppose that in runtime the program reads the expression (foo 3) from a text
file into a variable z (or even (setf z (read-from-string "(foo 3)"))), and
there is a call to

(eval z)

In delivery level 2 I get an error: undefined function FOO.
One way around it that I found is:

(defun bar ()
  (list #'foo))

and to call (bar) from another function (I'm sure there are similar ways).

But is there a more elegant way? All the functions that I want to use in the
text file are from the same package - perhaps this can help?

Thanks,
Iddo