Article is one in a list (4)
I believe the answer is:
item
This clue could be a double definition.
'article' is the first definition.
(I've seen this before)
'one in a list' is the second definition.
'item' can be an answer for 'one' (I've seen this before). I'm not sure about the 'in a list' bit.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for item that I've seen before include "Indivual unit" , "partners" , "Piece in paper" , "couple making out {TIME}..." , "Detail - entry" .)