Avoid John's broadcast (4)
I believe the answer is:
lose
'avoid' is the definition.
(lose can mean to avoid or dodge)
'john's broadcast' is the wordplay.
'john's' becomes 'loo's' (both can mean a toilet).
'broadcast' shows a homophone (sound like) (how the word might sound on the radio or TV).
'loos' is a homophone of 'LOSE'.
(Other definitions for lose that I've seen before include "Fail to win" , "Be beaten" , "Fail to keep" , "Misplace" , "Don't win" .)