Foreigner back from Breslau (4)
I believe the answer is:
serb
'foreigner back' is the definition.
Although both the answer and definition are adjectives, I can't see how they can define each other.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for serb that I've seen before include "Someone from Belgrade?" , "From Belgrade, perhaps" , "Balkan native" , "One from Belgrade" , "Native of the Balkans" .)