Support European partner (7)
I believe the answer is:
espouse
'support' is the definition.
(I've seen this before)
'european partner' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'partner' becomes 'spouse' (synonyms).
'e'+'spouse'='ESPOUSE'
(Other definitions for espouse that I've seen before include "See opus (anag)" , "Take in marriage" , "See opus to support a cause" , "Embrace" , "Give support to, say a cause" .)