Perfect international trade (5)
I believe the answer is:
ideal
'perfect' is the definition.
(similar in meaning)
'international trade' is the wordplay.
'international' becomes 'i' (abbreviation eg in IMF).
'trade' becomes 'deal' (synonyms).
'i'+'deal'='IDEAL'
(Other definitions for ideal that I've seen before include "Most suitable" , "Ailed (anag)" , "Paradigm" , "Utopian; yardstick" , "To which one aspires" .)