equivalent of make-local-variable for defun?

[jrwats]

I'm trying to fix a mode using comint for an inferior lisp that
apparently needs to overwrite  comint-send-region.  I'd rather it not
overwrite ALL buffers' (including my shell-mode buffer) comint-send-
region function.

Is there a way to define a function but local to the current buffer as
when you define a local variable in make-local-variable?