Famous? Not the media boss (5)
I believe the answer is:
noted
'famous?' is the definition.
(noted can mean well-known or famous)
'not the media boss' is the wordplay.
'the media boss' becomes 'ed' (short for editor).
'not'+'ed'='NOTED'
(Other definitions for noted that I've seen before include "Scored" , "Like music" , "Observed - famous" , "Remarkable" , "Significant" .)