Put off by the song during an act (7)
I believe the answer is:
delayed
'put off' is the definition.
(I've seen this before)
'song during an act' is the wordplay.
'song' becomes 'lay' (poetic term for a song).
'during' indicates putting letters inside.
'an act' becomes 'deed' (deed is a kind of act).
'lay' inserted inside 'deed' is 'DELAYED'.
'by the' is the link.
(Other definitions for delayed that I've seen before include "Shelved" , "Caused to be held up" , "Deferred, postponed" , "Put back" , "Protracted" .)