European in danger on that account (7)
I believe the answer is:
thereat
'on that account' is the definition.
(I've seen this in another clue)
'european in danger' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'in' indicates putting letters inside.
'danger' becomes 'threat' (threat can mean a danger or risk).
'e' placed within 'threat' is 'THEREAT'.
(Other definitions for thereat that I've seen before include "Theatre (anag)" , "At that point" , "At that place" , "On account of that" .)