Satan's reformed: he brings presents! (5)
I believe the answer is:
santa
'he brings presents' is the definition.
(Santa Claus delivers presents)
'satan's reformed' is the wordplay.
'reformed' is an anagram indicator.
'satan' anagrammed gives 'SANTA'.
(Other definitions for santa that I've seen before include "patron at Christmas" , "visitor bringing gifts" , "distributer of goodies" , "Children's name for Mr Claus" , "bringer of gifts" .)