Basement trader reportedly (6)
I believe the answer is:
cellar
'basement' is the definition.
('cellar' can be a synonym of 'basement')
'trader reportedly' is the wordplay.
'trader' becomes 'seller' (I've seen this before).
'reportedly' shows a homophone (sound like).
'seller' sounds like 'CELLAR'.
(Other definitions for cellar that I've seen before include "Underground area" , "Underground storeroom" , "Place for wine" , "Basement room, wine may be stored there" , "Storage area for the wine" .)