The press only partially blame Diana (5)
I believe the answer is:
media
'the press' is the definition.
(the press is part of the media)
'only partially blame diana' is the wordplay.
'only partially' says the answer is hidden in the clue.
'MEDIA' is hidden in the letters of 'blame diana'.
(Other definitions for media that I've seen before include "Television, papers, etc" , "Newspapers, TV, radio etc" , "News channels" , "Vehicles" , "Agencies" .)