Summon a coalition to control European country (6)
I believe the answer is:
monaco
'european country' is the definition.
(Monaco is an example)
'summon a coalition to control' is the wordplay.
'to control' indicates the answer is hidden within the clue (I've seen 'controlling' mean this (the solution is controlled or contained)).
'MONACO' can be found hidden inside 'summon a coalition'.
(Other definitions for monaco that I've seen before include "Oman Co. (anag)" , "Monte Carlo country" , "Constitutional monarchy on the French Riviera" , "Med principality" , "Southwest European principality" .)