In a perfect world, I had European associate (7)
I believe the answer is:
ideally
'in a perfect world' is the definition.
(I've seen this before)
'i had european associate' is the wordplay.
'i had' becomes 'id' (I'd).
'european' becomes 'e' (abbreviation e.g. EU).
'associate' becomes 'ally' (ally is a kind of associate).
'id'+'e'+'ally'='IDEALLY'
(Other definitions for ideally that I've seen before include "In the perfect case" , "In the best possible way or circumstances" , "Lay idle (anag)" , "in optimal way" , "for best results" .)