cause the downfall of someone in power (9) the person addressed (3) formal for during this month (4) musical instruments with strings over a flat box (7)
I have 'YoU', as 'the person addressed' , from 'cYst' and 'jUkebox'.
I couldn't use 'pulsars', as I had already used 'palette' for the artist's board.
There would appear to be no alternative but to use 'quasars', although 'pulsars' seems to be more accurate. There appeared to be no other clue which needed 'q'. Unless I have gone wrong!!!