Chaps feature this article penned by King (7)
I believe the answer is:
leather
'chaps feature this' is the definition.
(chaps are leather leg coverings)
'article penned by king' is the wordplay.
'article' becomes 'the' (the 'definite article' part of speech).
'penned by' is an insertion indicator.
'king' becomes 'lear' (I've seen this before).
'the' put inside 'lear' is 'LEATHER'.
(Other definitions for leather that I've seen before include "Flog; hide" , "Animal skins" , "Whip" , "calf" , "Treated hide" .)