Prospero's playing the tyrant (9)
I believe the answer is:
oppressor
'tyrant' is the definition.
(I've seen this before)
'prospero's playing' is the wordplay.
'playing' indicates anagramming the letters.
'prosperos' is an anagram of 'OPPRESSOR'.
'the' acts as a link.
(Other definitions for oppressor that I've seen before include "Persecutor of proposers" , "One tyrannises" , "Tyrant" , "One who keeps another in subjection" , "One subjects others to undue pressure" .)