The object of a piece of writing (7)
I believe the answer is:
article
This clue is a triple definition!
'the object' is the first definition.
(article is a kind of object)
'of' is a link.
'a piece' is the second definition.
(I've seen this before)
'of' acts as a link.
'writing' is the third definition.
(article is a kind of writing)
(Other definitions for article that I've seen before include "It could be the" , "Object and newspaper story" , "leader" , "You might say one" , "Division" .)