Generous artist included in defamatory publication (7)
I believe the answer is:
liberal
'generous' is the definition.
('liberal' can be similar in meaning to 'generous')
'artist included in defamatory publication' is the wordplay.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'included in' is an insertion indicator.
'defamatory publication' becomes 'libel' (I've seen this before).
'ra' going within 'libel' is 'LIBERAL'.
(Other definitions for liberal that I've seen before include "Lavish" , "Free - generous - politician" , "Bountiful" , "Ample; former politician" , "magnanimous" .)