One having a way of looking at river (6)
I believe the answer is:
angler
'one having' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'a way of looking at river' is the wordplay.
I cannot really see how this works, but
'a' could be 'an' and 'an' is found in the answer.
'way' could be 'e' (Compass direction - East) and 'e' is present in the answer.
'river' could be 'r' (abbreviation for river) and 'r' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for angler that I've seen before include "One proverbially exaggerating" , "One hoping for a catch" , "Fisher with rod and line" , "Hook and line fisherman" , "A rod and line fisherman" .)