Sportsman finds perspective by river (6)
I believe the answer is:
angler
'sportsman' is the definition.
(I've seen this before)
'perspective by river' is the wordplay.
'perspective' becomes 'angle' (angle is a kind of perspective).
'by river' becomes 'r' (abbreviation. I am not sure about the 'by' bit.).
'angle'+'r'='ANGLER'
'finds' is the link.
Can you help me to learn more?
(Other definitions for angler that I've seen before include "Sportsman" , "Isaac Walton wrote of the 'Compleat' one" , "I may do casting" , "Strait; -- of Lochalsh" , "A rod-and-line fisherman" .)