In a UK city near a river (4)
I believe the answer is:
tyne
'a river' is the definition.
(I've seen this before)
'in a uk city near' is the wordplay.
'in' says the answer is hidden in the clue.
'TYNE' can be found hidden inside 'uk city near'.
(Other definitions for tyne that I've seen before include "Serve as evidence for" , "Geordie river" , "Northumbrian river" , "River running through Newcastle" , "Banker" .)