Fine European nation under hot stream (6)
I believe the answer is:
influx
'stream' is the definition.
(I've seen this before)
'fine european nation under hot' is the wordplay.
'fine european nation' becomes 'flux' (I can't explain this - if you can you should give a lot more credence to this answer).
'under' is a charade indicator (letters next to each other).
'hot' becomes 'in' (both can mean fashionable).
'flux' put after 'in' is 'INFLUX'.
Can you help me to learn more?
(Other definitions for influx that I've seen before include "Large visitation" , "Mass arrival" , "Flow of people into a place" , "Act of flowing in" , "Sudden arrival in numbers" .)