Fantastic sunlit surroundings for river that's pristine (8)
I believe the answer is:
unspoilt
'pristine' is the definition.
(I know that pristine can be written as unspoilt)
'fantastic sunlit surroundings for river' is the wordplay.
'fantastic' indicates an anagram.
'surroundings for' indicates putting letters inside.
'river' becomes 'Po' (Italian river).
'sunlit' anagrammed gives 'unsilt'.
'unsilt' going around 'po' is 'UNSPOILT'.
'that's' is the link.
(Other definitions for unspoilt that I've seen before include "Not marred by development" , "Preserved" , "Natural - perfect" , "Natural, unsullied" , "Not harmed/damaged" .)