Widely divergent, like citizens of Warsaw and Cracow? (5,5)
I believe the answer is:
poles apart
'widely divergent' is the definition.
'poles apart' can be an answer for 'divergent' (thesaurus). I'm not certain of the 'widely' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for poles apart that I've seen before include "Goalposts are" , "far away from each other?" , "Having widely divergent opinions" , "Unlikely to meet" , "Completely different" .)