Twice the profit on an article (5)
I believe the answer is:
again
'twice' is the definition.
(I've seen this in another clue)
'profit on an article' is the wordplay.
'profit' becomes 'gain' (synonyms).
'on' says to put letters next to each other.
'an article' becomes 'a' (English indefinite article).
'gain' put after 'a' is 'AGAIN'.
'the' acts as a link.
(Other definitions for again that I've seen before include "Not for the first time" , "Here we go ___" , "10 10 [AGAIN" , "Ocne more" , "Anew" .)