No place for involving more than one river (4)
I believe the answer is:
ural
'river' is the definition.
(Russian river)
'no place for involving more than one' is the wordplay.
I cannot quite see how this works, but
'one' could be 'a' (a thing is one thing) and 'a' is present in the answer.
The remaining letters 'url' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ural that I've seen before include "Runner" , "Russian river flowing into the Caspian Sea" , "Russian river giving name to mountain range" , "River of central Russia" , "The - mountains separate Asia and Europe" .)