To Ann, he's a changed man (5)
I believe the answer is:
'man' is the definition.
(I've seen this before)
'to ann he's a changed' is the wordplay.
'to ann' anagrams to 'ANTON'.
However, I'm not clear how this is indicated.
Can you help me to learn more?
(Other definitions for anton that I've seen before include "Boy" , "-- Bruckner, composer" , "..... Chekov" , "Chekhov maybe" , "Chekhov, say" .)