Nonbinary pronoun (4)
'nonbinary pronoun' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for them that I've seen before include "Certainly not us, the other lot" , "Others" , "(To/from) those people" , "Perhaps, the Opposition" , "Those people (as object)" .)
(Other definitions for they that I've seen before include "Third person plural" , "Pronoun for people" , "People generally" , "Pronoun for more than one" , "People in general" .)