Row about journalist in decline (9)
I believe the answer is:
reduction
'decline' is the definition.
(thesaurus)
'row about journalist' is the wordplay.
'row' becomes 'ruction' (**).
'about' means one lot of letters goes inside another.
'journalist' becomes 'ed' (short for editor).
'ruction' placed around 'ed' is 'REDUCTION'.
'in' acts as a link.
(Other definitions for reduction that I've seen before include "Introduce (anag) - decrease" , "Lessening" , "Decrease, diminution" , "Introduce by way of discount" , "from nine to five, for example" .)