Problematic situation involving power following European sovereignty (6)
I believe the answer is:
empire
'sovereignty' is the definition.
(thesaurus)
'problematic situation involving power following european' is the wordplay.
'problematic situation' becomes 'mire' (mire can mean a complex or difficult situation).
'involving' indicates putting letters inside.
'power' becomes 'p'.
'following' says to put letters next to each other.
'european' becomes 'e' (abbreviation e.g. EU).
'mire' enclosing 'p' is 'mpire'.
'mpire' after 'e' is 'EMPIRE'.
(Other definitions for empire that I've seen before include "Widespread political or industrial organisation" , "Wide dominion" , "Group of states under the control one authority" , "The domain of a ruler" , "Sovereign state" .)