Fierce fighting in Brazilian city (6)
I believe the answer is:
recife
'brazilian city' is the definition.
(I know that Recife is a metropolis)
'fierce fighting' is the wordplay.
'fighting' indicates an anagram (I've seen this in other clues).
'fierce' with letters rearranged gives 'RECIFE'.
'in' is the link.
(Other definitions for recife that I've seen before include "Atlantic port" , "South American port" .)