Those people show what Donald Trup is missing (4)
I believe the answer is:
them
'those people' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
(Other definitions for them that I've seen before include "Others" , "Certainly not us, the other lot" , "(To/from) those people" , "... in another case, they" , "people objectively" .)