Remove [[:Category:Italian verb forms]] when {{temp|head|it|verb form}} is present.
Fragment of a discussion from User talk:Rua
Oh like that. It's possible but it's not easy to do. The problem is knowing which entries have it and which don't. The simplest way I know of would be rather invasive at least temporarily: edit Module:headword so that it does not add "Italian verb forms" and then remove the category from any that remain in Category:Italian verb forms, until it's empty, then restore Module:headword again.