Article new at that time (4)
I believe the answer is:
'at that time' is the definition.
('then' can be a synonym of 'at that time')
'article new' is the wordplay.
'article' becomes 'the' (the 'definite article' part of speech).
'new' becomes 'n'.
(Other definitions for then that I've seen before include "soon?" , "At that time; next" , "Once upon a time" , "Subsequently - previously" , "Afterwards - as a result" .)