The debian/clean file can list other files to be removed.
It does not run "make clean" to clean up after the build process. Use
-L<dh_auto_clean(1)> to do that.
+L<dh_auto_clean(1)> to do things like that.
dh_clean (or "dh clean") should be the last debhelper command run in the
clean target in debian/rules.