Failed to take down broadcast (4)
I believe the answer is:
blew
'failed' is the definition.
(blowing is a kind of failing)
'down broadcast' is the wordplay.
'down' becomes 'blue' (both can mean sad).
'broadcast' indicates a 'sounds like' (homophone) clue (how the word might sound on the radio or TV).
'blue' sounds like 'BLEW'.
'to take' is the link.
(Other definitions for blew that I've seen before include "Squandered" , "Breathed hard" , "Sounded (a whistle)" , "Squander in the past" , "Tooted" .)