Leader in media having no case to retreat back (9)
I believe the answer is:
editorial
'leader' is the definition.
(type of newspaper article)
'media having no case to retreat back' is the wordplay.
'having no case' means to look at the middle letters (letters which encase the word are removed).
'retreat' becomes 'lair' (both can mean a private hideout).
'back' shows that the letters should be reversed in order.
The centre of 'media' is 'edi'.
'lair' backwards is 'rial'.
'edi'+'to'+'rial'='EDITORIAL'
'in' is the link.
(Other definitions for editorial that I've seen before include "Article that states a newspaper's opinion" , "(Paper's) leader" , "Article expressing the views of the publication" , "Newspaper article - "I led a riot" (anag)" , "matter of opinion" .)