Some populist unfortunate from Knock (4)
I believe the answer is:
stun
'knock' is the definition.
(thesaurus)
'some populist unfortunate from' is the wordplay.
'from' says the answer is hidden in the clue.
'STUN' is hidden in the letters of 'some populist unfortunate'.
(Other definitions for stun that I've seen before include "Shock or astonish" , "Concuss, stupefy" , "Daze with nuts" , "Knock cold" , "Dumbfound" .)