Start to boo the act now playing? (4,2)
I believe the answer is:
turn on
'start' is the definition.
(thesaurus)
'boo the act now playing?' is the wordplay.
'boo the act now' becomes 'turn' (I can't explain this - if you can you should believe this answer much more).
'playing?' becomes 'on' (on can mean playing or performing).
'turn'+'on'='TURN-ON'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for turn on that I've seen before include "Start; become hostile towards" , "Excite sexually" , "Person with twenty five [SEX APPEAL]" , "Person or thing with the ability to excite" , "Start working" .)