He likes to improve things for the anagrammatist (8)
I believe the answer is:
reformer
'he likes to improve things for the anagrammatist' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he likes to' is the wordplay.
I cannot quite understand how this works, but
'to' could be 'for' and 'for' is located in the answer.
'he' could be 'rem' and 'rem' is found in the remaining letters.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for reformer that I've seen before include "eg Luther" , "Luther, perhaps" , "One who changes or improves, say, an organisation" , "Luther, for one" , "One changing for the better" .)