Naming word (4)
I believe the answer is:
noun
'naming word' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for noun that I've seen before include "Substantive word" , "Type of word" , "Part of speech identifying a person, place or thing" , "Person, place, thing, state or quality?" , "Naming word (grammar)" .)