`eval'ing form in the current lexical environment

[Thuna]

How would I `eval' a form as though it were where the `(eval ...)' form
was?  That is, is there an argument to LEXICAL I can pass such that
  (... (eval form LEXICAL) ...)
becomes identical to
  (... <value-of-form> ...)

Let me state my problem as well, in case anyone knows of a solution to
that: I have a macro which modifies the form fed to it, macroexpanding
it as necessary.  Functions are handled specifically, in that its
arguments are computed and the call to the function replaced by
  (func arg1 arg2...)
If, however, `func' is then redefined as a macro, and uses one of its
args without evaluating it, then this would understandably break.  At
the same time, the process the original form went through in my macro is
one that this now-macro form needs to go through as well, so I expand
into a form which *during evaluation* calls this process on the literal
form which is fed to it and evals it.  This all looks something like
  (defmacro (lambda-list head &rest args)
    `(defun ,lambda-list
       ...
       (if (macrop #',head)
           (eval (<processor> '(,head ,@args)))
         (,head ,@argsyms))))
and it is absolutely expected for the forms in ARGS to be aware of and
reference the variables established in LAMBDA-LIST, but because of the
above problem that is not the case (as far as I could tell).