Cambridgeshire cathedral (3)
I believe the answer is:
ely
'cambridgeshire cathedral' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ely that I've seen before include "'Isle' in Cambridgeshire" , "Cathedral city in East Anglia" , "Small city in Cambridgeshire" , "UK city" , "Cathedral city in Cambridgeshire" .)