One making alterations to one's character in Luther, for instance
I believe the answer is:
reformer
'one making alterations to one's character in luther for instance' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'one making alterations to one's character' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is found within the answer.
'to' could be 'for' and 'for' is found in the answer.
'character' could be 'r' and 'r' is found within the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for reformer that I've seen before include "One who changes organisation in order to improve" , "Luther, perhaps" , "One dealing with abuses" , "Person who advocates change" , "eg Luther" .)