River animal died — one struck by arrows (9)
I believe the answer is:
dartboard
'one struck by arrows' is the definition.
'river animal died' is the wordplay.
'river' becomes 'dart' (River Dart in Devon**).
'animal' becomes 'boar' (I've seen this before).
'died' becomes 'd'.
'dart'+'boar'+'d'='DARTBOARD'
(Other definitions for dartboard that I've seen before include "Target for arrows" , "Pub game equipment" , "It's doubles all round" , "Target found in pubs" .)