Rock, paper, or scissors (4)
I believe the answer is:
noun
'rock paper or scissors' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for noun that I've seen before include "Category of word" , "Part of speech identifying a person, place or thing" , "Person, place, thing, state or quality?" , "Naming word (grammar)" , "Word identifying person, place or thing" .)