What causes destruction of half of east European capital (4)

I believe the answer is:

pest

I'm a little stuck... Click here to teach me more about this clue!

'destruction of half of east european capital' is the definition.
'pest' can be an answer for 'destruction' (thesaurus). I'm not sure about the 'of half of east european capital' bit.

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for pest that I've seen before include "Menace" , "Constant nuisance" , "Destructive insect or other animal" , "Troublesome man or animal" , "Annoying thing" .)

I've seen this clue in The Times.

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