Chorus of "Desist!" (7)
I believe the answer is:
refrain
I believe this is a double definition.
'chorus' is the first definition.
(I know that chorus can be written as refrain)
'desist' is the second definition.
(I know that desist can be written as refrain)
'of' is the link.
(Other definitions for refrain that I've seen before include "Do without" , "Stop activity" , "burden" , "Chorus; keep away (from)" , "Don't do that - it's a song" .)