Country dancing is at one (7)
I believe the answer is:
estonia
'country' is the definition.
(I've seen this before)
'dancing is at one' is the wordplay.
'dancing' indicates anagramming the letters.
'is'+'at'+'one'='isatone'
'isatone' with letters rearranged gives 'ESTONIA'.
(Other definitions for estonia that I've seen before include "So eat in about here in Northern Europe" , "'So eat in here in Tallinn, say (7)'" , "Country on the Baltic Sea" , "Northern European country" , "European country, capital Tallinn" .)