Padre does reform a criminal (9)
I believe the answer is:
desperado
'a criminal' is the definition.
(desperado is a kind of criminal)
'padre does reform' is the wordplay.
'reform' indicates anagramming the letters.
'padre'+'does'='padredoes'
'padredoes' anagrammed gives 'DESPERADO'.
(Other definitions for desperado that I've seen before include "Bold outlaw on the American frontier" , "reckless type" , "Reckless criminal" , "Road speed (anag.)" , "Bravo" .)