Sound of shopkeeper in basement (6)
I believe the answer is:
cellar
'basement' is the definition.
(basement room)
'sound of shopkeeper' is the wordplay.
'sound of' indicates a 'sounds like' (homophone) clue.
'shopkeeper' becomes 'seller' (someone who sells things).
'seller' sounds like 'CELLAR'.
'in' acts as a link.
(Other definitions for cellar that I've seen before include "Storage area for the wine" , "Wine vault" , "Underground store room" , "Storage space, for wine perhaps" , "Underground room - stock of bottled wines" .)