Broadcast small conclusion (4)
I believe the answer is:
send
'broadcast' is the definition.
(I know that broadcast can be written as send)
'small conclusion' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'conclusion' becomes 'end' (something's conclusion is its end).
's'+'end'='SEND'
(Other definitions for send that I've seen before include "Transport" , "broadcast" , "Dispatch by post" , "Mail" , "Despatch, remit" .)