Possibly posh emporium (4)
I believe the answer is:
shop
'emporium' is the definition.
(thesaurus)
'possibly posh' is the wordplay.
'possibly' indicates an anagram.
'posh' anagrammed gives 'SHOP'.
(Other definitions for shop that I've seen before include "Betray - place selling things" , "Establishment for the sale of goods" , "Store, outlet" , "Where goods are bought and sold" , "Give away" .)