Hiker, person walking past river (7)
I believe the answer is:
rambler
'hiker' is the definition.
(I've seen this before)
'person walking past river' is the wordplay.
I cannot really see how this works, but
'river' could be 'r' (abbreviation for river) and 'r' is located in the answer.
The remaining letters 'ambler' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rambler that I've seen before include "Trailing climbing plant" , "who's not heading for the point" , "Presumably one goes on" , "Hiker" , "country activist" .)