It has steep sides and is found in Tuscany only (6)
I believe the answer is:
canyon
'it has steep sides and is' is the definition.
The definition suggests a singular noun which matches the answer.
'in tuscany only' is the wordplay.
'in' indicates the answer is hidden within the clue.
'CANYON' is hidden within 'tuscany only'.
'found' acts as a link.
Can you help me to learn more?
(Other definitions for canyon that I've seen before include "'Deep ravine, gorge (6)'" , "Deep, steep-sided valley" , "grand spectacle in Arizona" , "Gulf" , "deep container for water" .)