Taking this recent question as an example, word/phrase request questions frequently get answers for many different word classes. It has several verbs and adjectives, and 'tooth and nail' would be an adverb I guess.
The close reason for off-topic word/phrase requests is:
Questions on choosing an ideal word or phrase must include information on how it will be used in order to be answered. For help writing a good word or phrase request, see: About single word requests
The linked page says:
Describe the intended meaning, connotation, and/or context in as much detail as you can. ... Does the question describe exactly in what context you want to use a single word?
I think that it should be required for these request questions to specify if they are after a noun, verb, adjective etc. Those that do not should be closed. I think it would be helpful for the tag wiki page to be edited to explain that part of what 'describing the context' means is to specify a word class.