Passable trade show (4)
I believe the answer is:
fair
This clue is a double definition.
'passable' is the first definition.
(synonyms)
'trade show' is the second definition.
(I've seen this before)
(Other definitions for fair that I've seen before include "Satisfactory" , "Attractive type of weather?" , "Treating people equally" , "Just right" , "Where the helter-skelter may be" .)