Writing about Rome, I digress in the autobiography (7)
I believe the answer is:
memoirs
'the autobiography' is the definition.
(I've seen this in another clue)
'writing about rome i digress in' is the wordplay.
'writing about' indicates anagramming the letters (letters moved around or about).
'digress' becomes 'ms' (I am not sure about this - if you are sure you should believe this answer much more).
'in' indicates putting letters inside.
'rome'+'i'='romei'
'romei' anagrammed gives 'emoir'.
'emoir' put into 'ms' is 'MEMOIRS'.
Can you help me to learn more?
(Other definitions for memoirs that I've seen before include "Published reminiscences" , "Accounts of personal experiences" , "Autobiography?" , "Memo, sir about accounts of past events" , "Autobiographical account" .)