Flies to Niagara, taking in country (7)
I believe the answer is:
estonia
'country' is the definition.
(European country)
'flies to niagara taking' is the wordplay.
'taking' says the answer is hidden in the clue (the answer is carried or taken by the clue).
'ESTONIA' is hidden within 'flies to niagara'.
'in' acts as a link.
(Other definitions for estonia that I've seen before include "Country due S. of Finland" , "Baltic republic, capital Tallinn" , "Republic in the Baltic region, once part of USSR" , "So eat in poorly on the Baltic Sea" , "So eat in here in Eastern Europe" .)