Article in paper is a hoax (6)
I believe the answer is:
canard
'a hoax' is the definition.
(I've seen this before)
'article in paper' is the wordplay.
'article' becomes 'an' (indefinite article).
'in' means one lot of letters goes inside another.
'paper' becomes 'card' (card is a kind of paper).
'an' put within 'card' is 'CANARD'.
'is' acts as a link.
(Other definitions for canard that I've seen before include "Unfounded rumour or story" , "False rumour also from France" , "False rumour or story, from France" , "False rumour, originally from France" , "Ugly rumour" .)