Rouse start of play and a TV broadcast with energy (8)
I believe the answer is:
activate
'rouse' is the definition.
(thesaurus)
'start of play and a tv broadcast with energy' is the wordplay.
'start of play' becomes 'act i' (Act I).
'and' says to put letters next to each other.
'broadcast with' indicates an anagram (letters scattered or cast around).
'energy' becomes 'e' (physics symbol as in E=mc2).
'a'+'tv'='atv'
'atv' mixed up with 'e' gives 'vate'.
'acti'+'vate'='ACTIVATE'
(Other definitions for activate that I've seen before include "Give life to" , "Prompt" , "Cause to move or start" , "Stimulate to action" , "Energise" .)