Battle cry around the City (5)
I believe the answer is:
crecy
'battle' is the definition.
(I know that Crecy is a pitched battle)
'cry around the city' is the wordplay.
'around' is an insertion indicator.
'the city' becomes 'EC' (the City of London postcode).
'cry' enclosing 'ec' is 'CRECY'.
(Other definitions for crecy that I've seen before include "Where Black Prince won spurs" , "Thirteen fourty six win for Edward III" .)