River that starts in the Swiss Alps (5)
I believe the answer is:
rhine
'river that starts in the swiss alps' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rhine that I've seen before include "Great river that flows through Germany" , "water" , "Bonn's river" , "Great German river with Lorelei Rock" , "Cologne's river" .)