City ends in triumph against Real (4)
I believe the answer is:
echt
'real' is the definition.
(I've seen this before)
'city ends in triumph against' is the wordplay.
'city' becomes 'EC' (postcode for the City of London).
'ends in' indicates one should take the final letters.
The final letters of 'triumph against' are 'ht'.
'ec'+'ht'='ECHT'
(Other definitions for echt that I've seen before include "Genuine -- honest" , "Really" , "True" , "Genuine (German)" , "German's real" .)