One spring flower missing in eastern country (7)
I believe the answer is:
iceland
'one spring flower' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'missing in eastern country' is the wordplay.
'missing in' becomes 'ic' (I can't justify this - if you can you should give a lot more credence to this answer).
'eastern' becomes 'e'.
'country' becomes 'land' ('land' can be a synonym of 'country').
'ic'+'e'+'land'='ICELAND'
(Other definitions for iceland that I've seen before include "Northern country" , "Althing its parliament" , "European island country" , "Cold Atlantic country" , "Nice lad (anag)" .)