Cut off city in a harsh way (8)
I believe the answer is:
severely
'in a harsh way' is the definition.
(I've seen this in another clue)
'cut off city' is the wordplay.
'cut off' becomes 'sever' (to sever is to cut).
'city' becomes 'ely' (Ely is a city in Cambridgeshire).
'sever'+'ely'='SEVERELY'
(Other definitions for severely that I've seen before include "Sternly or gravely" , "in a very plain style" , "very badly" , "Strictly, harshly" , "In a stern manner" .)