Minister in power tries to reform (6)
I believe the answer is:
priest
'minister' is the definition.
(thesaurus)
'power tries to reform' is the wordplay.
'power' becomes 'p' (**).
'to reform' indicates anagramming the letters.
'tries' anagrammed gives 'riest'.
'p'+'riest'='PRIEST'
'in' acts as a link.
(Other definitions for priest that I've seen before include "Man of the cloth" , "Conductor of religious service" , "Art looking into" , "Stripe for a cleric" , "Religious teacher" .)