Damn former City charge (8)
I believe the answer is:
execrate
'damn' is the definition.
(thesaurus)
'former city charge' is the wordplay.
'former' becomes 'ex'.
'city' becomes 'ec' (the City of London postcode).
'charge' becomes 'rate' (rate is a kind of charge**).
'ex'+'ec'+'rate'='EXECRATE'
(Other definitions for execrate that I've seen before include "Express great loathing for" , "Utter curses with erect axe" , "'Abhor, find repugnant (8)'" , "Feel great loathing for" , "Damn" .)