Maybe one in Serbia is a very large area (7)
I believe the answer is:
siberia
'area' is the definition.
(Siberia is an example)
'maybe one in serbia is a very large' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
an anagram of 'serbia' is 'sberia' which is present in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for siberia that I've seen before include "Vast Asian region of Russia" , "Former place of exile for a Russian" , "Russian far-east" , "Region of Russia, from the Urals to the Pacific, famously cold in winter" , "Russian region in N Asia noted for harsh winters and prison camps" .)