Article is essential piece of incitement (4)
I believe the answer is:
item
'article' is the definition.
(I've seen this before)
'essential piece of incitement' is the wordplay.
'essential piece of' indicates a hidden word (the solution forms a piece of the clue).
'ITEM' is hidden within 'incitement'.
'is' is the link.
(Other definitions for item that I've seen before include "Entry (in an account)" , "One article" , "Two in a romantic relationship?" , "One thing among many" , "newspaper article" .)