Broadcast a tirade when upset (7)
I believe the answer is:
radiate
'broadcast' is the definition.
(thesaurus)
'a tirade when upset' is the wordplay.
'when upset' indicates anagramming the letters.
'a'+'tirade'='atirade'
'atirade' is an anagram of 'RADIATE'.
(Other definitions for radiate that I've seen before include "Give out (light, etc)" , "Spoke out" , "broadcast" , "Emit (light, heat, etc)" , "Disseminate" .)