Fuming Queen upset European ruler (7)
I believe the answer is:
reeking
'fuming' is the definition.
('reek' can be a synonym of 'fume')
'queen upset european ruler' is the wordplay.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'upset' is a reversal indicator.
'european' becomes 'E' (abbreviation e.g. EU).
'ruler' becomes 'king' (king is a kind of ruler).
'er' in reverse letter order is 're'.
're'+'e'+'king'='REEKING'
(Other definitions for reeking that I've seen before include "Stinking" , "Giving off a strong smell" , "Emitting smoke" , "Having a foul smell" , "With a very unpleasant smell" .)