Broadcast second conclusion (4)
I believe the answer is:
send
'broadcast' is the definition.
(synonyms)
'second conclusion' is the wordplay.
'second' becomes 's' (common abbreviation).
'conclusion' becomes 'end' (something's conclusion is its end).
's'+'end'='SEND'
(Other definitions for send that I've seen before include "Transmit; post" , "broadcast" , "Consign" , "and 2: Advise" , "Cause to go for" .)