A tirade might be broadcast (7)
I believe the answer is:
radiate
'broadcast' is the definition.
(I've seen this before)
'a tirade might be' is the wordplay.
'might be' indicates anagramming the letters.
'a'+'tirade'='atirade'
'atirade' anagrammed gives 'RADIATE'.
(Other definitions for radiate that I've seen before include "Emit rays; diverge" , "Give out (light, etc)" , "Spread outwards" , "Shine" , "Emit light/heat" .)