Author from Sicily and I fled valley, falling into Italian river (10)
I believe the answer is:
pirandello
'author' is the definition.
(I know that Pirandello is a novelist)
'i fled valley falling into italian river' is the wordplay.
'fled' becomes 'ran' (ran away).
'valley' becomes 'dell' (dell is a kind of valley).
'falling into' means one lot of letters goes inside another.
'italian river' becomes 'po' (river in Italy).
'i'+'ran'+'dell'='irandell'
'irandell' placed inside 'po' is 'PIRANDELLO'.
'from sicily and' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for pirandello that I've seen before include "Be in complete control" , "Italian short story writer" , "Luigi -, Italian playwright (Six Characters in Search of an Author)" , "writer found" , "Sicilian dramatist" .)