Shut up, declines to be set free (8)
I believe the answer is:
silenced
'shut up' is the definition.
(I've seen this in another clue)
'declines to be set free' is the wordplay.
'to be set free' indicates an anagram.
'declines' with letters rearranged gives 'SILENCED'.
(Other definitions for silenced that I've seen before include "Declines to be made mute" , "Gagged" , "cut short" , "Declines to be made quiet" , "shut up" .)