Stuck on last three in top right:
7D Writer is brought into rock band to make music (8) ?O?O?I??
6D BAnd, live, including old instrument for blowing in the wind (4) Second half of clue suggests an obvious write-in but parsing?
20A Backed a time and place for big event (5) A???A
Again, a fairly obvious write-in but why?
Strong hints welcome.