Nerves are bad at the British river (6)
I believe the answer is:
severn
(Other definitions for severn that I've seen before include "Running water" , "Gloucester's river" , "Longest UK river" , "West Country river" , "River with famous bore" .)
I believe the answer is:
severn
(Other definitions for severn that I've seen before include "Running water" , "Gloucester's river" , "Longest UK river" , "West Country river" , "River with famous bore" .)