Net locator crosses a river (4)
I believe the answer is:
ural
'river' is the definition.
(I've seen this before)
'net locator crosses a' is the wordplay.
'net locator' becomes 'url' (I can't explain this - if you can you should give a lot more credence to this answer).
'crosses' is an insertion indicator.
'url' placed around 'a' is 'URAL'.
Can you help me to learn more?
(Other definitions for ural that I've seen before include "The .... Mountains divide Europe and Asia" , "2,400 km river flowing through Russia and Kazakhstan into the Caspian Sea" , "Russian river flowing into the Caspian Sea" , "Europe/Asia river" , "Runner" .)