Lake in the Sierra Nevada (5)
I believe the answer is:
tahoe
'lake in the sierra nevada' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tahoe that I've seen before include "the Nevada/California border area" , "Lake in Sierra Nevada mountains" , "Lake/desert resort on the California-Nevada border" , "Nevada/California lake" , "US lake" .)