Geographical feature seen in Tuscany only (6)
I believe the answer is:
canyon
'geographical feature' is the definition.
(I've seen this before)
'in tuscany only' is the wordplay.
'in' indicates a hidden word.
'CANYON' is hidden within 'tuscany only'.
'seen' is the link.
(Other definitions for canyon that I've seen before include "grand spectacle in Arizona" , "Narrow steep-sided valley" , "deep container for water" , "Deep valley with steep, even Grand, slopes" , "geographical feature" .)