Previous location of a trade fair (10)
I believe the answer is:
exposition
'a trade fair' is the definition.
(thesaurus)
'previous location' is the wordplay.
'previous' becomes 'ex' (prefix meaning former or onetime).
'location' becomes 'position' (synonyms).
'ex'+'position'='EXPOSITION'
'of' acts as a link.
(Other definitions for exposition that I've seen before include "Public display" , "commentary" , "Account" , "large show" , "fair" .)