River flowing through York (4)
I believe the answer is:
ouse
'river flowing through york' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ouse that I've seen before include "York's river" , "One of several rivers" , "River that joins the Trent to form the Humber" , "bird has lost its tail" , "River flowing through York" .)