Writer's novel surmised penned after leaving Italy (6,7)
I believe the answer is:
edmund spenser
'writer's' is the definition.
I know nothing about this answer so I can't judge whether this works.
'novel surmised penned after leaving italy' is the wordplay.
'novel' indicates anagramming the letters (letters in a new or novel order).
'after leaving' indicates named letters should be taken away.
'italy' becomes 'i'.
'surmised'+'penned'='surmisedpenned'
'surmisedpenned' with 'i' taken away is 'surmsedpenned'.
'surmsedpenned' with letters rearranged gives 'EDMUND SPENSER'.
Can you help me to learn more?
(Another definition for edmund spenser that I've seen is " poet".)