Defamed a journalist backing press changes (8)
I believe the answer is:
aspersed
'defamed' is the definition.
('asperse' can be a synonym of 'defame')
'a journalist backing press changes' is the wordplay.
'journalist' becomes 'ed' (short for editor).
'backing' means one lot of letters go next to another.
'changes' indicates an anagram.
'press' with letters rearranged gives 'spers'.
'ed' after 'spers' is 'spersed'.
'a'+'spersed'='ASPERSED'
(Other definitions for aspersed that I've seen before include "Defamed" , "Made false allegations" , "Abused" , "Slandered" , "Calumniated" .)