Rare gems scattered in lake (8)
I believe the answer is:
grasmere
'lake' is the definition.
(I've seen this before)
'rare gems scattered' is the wordplay.
'scattered' is an anagram indicator.
'rare'+'gems'='raregems'
'raregems' with letters rearranged gives 'GRASMERE'.
'in' acts as a link.
(Other definitions for grasmere that I've seen before include "Wordsworth's village" , "De Quincey at home here" , "Wordsworth's Lake District home" , "Wordsworth dwelt" .)