Broadcaster leaves to shoot up (9)
I believe the answer is:
skyrocket
'shoot up' is the definition.
(thesaurus)
'broadcaster leaves' is the wordplay.
'broadcaster' becomes 'sky' (Sky is a television company).
'leaves' becomes 'rocket' (I've seen this before).
'sky'+'rocket'='SKYROCKET'
'to' acts as a link.
(Other definitions for skyrocket that I've seen before include "Shoot up high" , "Increase very rapidly" , "Rapidly appreciate" , "Mushroom" , "seen to shoot up" .)