Broadcaster's worse when excited (5)
I believe the answer is:
sower
'broadcaster's' is the definition.
(someone who broadcasts or sows seeds)
'worse when excited' is the wordplay.
'when excited' indicates anagramming the letters.
'worse' with letters rearranged gives 'SOWER'.
(Other definitions for sower that I've seen before include "Seedy operative" , "Farm worker" , "One spreading seeds" , "Worker in field" , "Arable worker" .)