In his wickedness, there's not much remorse (5)
I believe the answer is:
simon
'much remorse' is the definition.
The definition suggests a singular noun which matches the answer.
'in his wickedness there's not' is the wordplay.
'in' indicates putting letters inside.
'his wickedness' becomes 'sim' (I can't justify this - if you can you should believe this answer much more).
'there's' becomes 'n' (I've seen this in other clues).
'not' becomes 'o' (I've seen this in other clues).
'sim'+'n'='simn'
'simn' enclosing 'o' is 'SIMON'.
Can you help me to learn more?
(Other definitions for simon that I've seen before include "disciple" , "Fellow" , "One of Christ's apostles" , "- Templar, The Saint" , "He's simple in rhyme" .)