Saint with his own method of penetrating evil (5)
I believe the answer is:
simon
'saint' is the definition.
(I know that Simon is a saint)
'method of penetrating evil' is the wordplay.
'method of' becomes 'mo' (this could be a standard abbreviation of which I'm unaware).
'penetrating' indicates putting letters inside.
'evil' becomes 'sin' (synonyms).
'mo' put inside 'sin' is 'SIMON'.
'with his own' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for simon that I've seen before include "Peter (NT)" , "Bolivar, de Montfort, Callow or Cowell?" , "See 1" , "Man" , "A simple character in nursery rhyme" .)