Baron associated with timeless TV corporation (5)
I believe the answer is:
belly
'corporation' is the definition.
(corporation can humorously mean belly fat)
'baron associated with timeless tv' is the wordplay.
'baron' becomes 'b'.
'associated with timeless tv' becomes 'elly' (I can't justify this - if you can you should believe this answer much more).
'b'+'elly'='BELLY'
(Other definitions for belly that I've seen before include "Paunch" , "Tummy" , "Stomach" , "Abdomen" , "Corporation" .)