Atoms spinning round in north-eastern state (9)
I believe the answer is:
minnesota
'state' is the definition.
(Minnesota is an example)
'atoms spinning round in north-eastern' is the wordplay.
'spinning' is an anagram indicator.
'round' is an insertion indicator.
'north' becomes 'N' (abbreviation).
'eastern' becomes 'e'.
'atoms' anagrammed gives 'msota'.
'in'+'n'+'e'='inne'
'msota' placed around 'inne' is 'MINNESOTA'.
(Other definitions for minnesota that I've seen before include "source of iron ore" , "American state, capital St Paul" , "North Star State" , "Nominates for American state" , "Nominates, oddly, the US state" .)