Wandered, but remained around river (7)
I believe the answer is:
strayed
'wandered' is the definition.
('stray' can be a synonym of 'wander')
'remained around river' is the wordplay.
I cannot really understand how this works, but
'river' could be 'r' (abbreviation for river) and 'r' is found in the answer.
'remained' could be 'stayed' ('stay' can be a synonym of 'remain') and 'stayed' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'but' is the link.
Can you help me to learn more?
(Other definitions for strayed that I've seen before include "Wandered (from path)" , "Went off violin" , "Went off course" , "Erred, wandered" , "Wandered; digressed" .)