A life of someone by himself? (13)
I believe the answer is:
autobiography
'himself?' is the definition.
I can't tell whether this definition defines the answer.
'a life of someone by' is the wordplay.
'a life' becomes 'biography' ('biography' can be a synonym of 'life').
'of someone' becomes 'auto' (I am not sure about this - if you are sure you should believe this answer much more).
'by' says to put letters next to each other.
'biography' put after 'auto' is 'AUTOBIOGRAPHY'.
Can you help me to learn more?
(Other definitions for autobiography that I've seen before include "Memoirs" , "A person's account of their life" , "Story of one's life" , "Person's life story written by the subject" , "Personal account of one's life" .)