In France you cast your eye over unknown part of Italy (7)
I believe the answer is:
tuscany
'part of italy' is the definition.
('Tuscany' is part of 'italy')
'in france you cast your eye over unknown' is the wordplay.
I cannot really understand how this works, but
'you' could be 'u' (commonly used in online communication) and 'u' is located in the answer.
an anagram of 'cast' is 'tsca' which is present in the remaining letters.
'unknown' could be 'y' (algebra) and 'y' is located in the answer.
A single letter 'n' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for tuscany that I've seen before include "Italian region, capital Florence" , "part of Italy" , "N. Italian region" , "Region of Central Italy, chief city Florence." , "'Chiantishire'" .)