River rising high in northern Europe, initially (5)
I believe the answer is:
rhine
'river' is the definition.
(Rhine is an example)
'rising high in northern europe initially' is the wordplay.
'initially' says to take the initial letters.
The initial letters of 'rising high in northern europe' is 'RHINE'.
(Other definitions for rhine that I've seen before include "River at Bonn, Koln" , "valley" , "River, rising in Switzerland and flowing into the North Sea" , "Great river in Germany with Lorelei Rock" , "Great river that flows through Germany" .)