Not just an international trade show (6)
I believe the answer is:
unfair
'not just' is the definition.
('unfair' is the opposite to 'just')
'an international trade show' is the wordplay.
'an international' becomes 'un' (I've seen this in other clues).
'trade show' becomes 'fair' (I've seen this before).
'un'+'fair'='UNFAIR'
(Other definitions for unfair that I've seen before include "Partisan" , "Not just - lacking in beauty" , "Weighted" , "raining perhaps?" , "Unjust, partial" .)