Trade fairs lead to enrichment, a revelation (6)
I believe the answer is:
expose
'a revelation' is the definition.
(expose is a kind of revelation)
'trade fairs lead to enrichment' is the wordplay.
'trade fairs' becomes 'expos'.
'lead to' indicates taking the first letters.
The initial letter of 'enrichment' is 'e'.
'expos'+'e'='EXPOSE'
(Other definitions for expose that I've seen before include "outing" , "Lay bare" , "Disclose" , "Uncover, expose to view" , "article on scandal?" .)