Strange-sounding sale (6)
I believe the answer is:
bazaar
'sale' is the definition.
(I know that bazaar is a type of sale)
'strange-sounding' is the wordplay.
'strange' becomes 'bizarre' (synonyms).
'sounding' shows a homophone (sound like).
'bizarre' sounds like 'BAZAAR'.
(Other definitions for bazaar that I've seen before include "Where many would shop" , "Souk" , "Street of small shops in the Orient" , "Group of stalls in oriental country" , "Group of shops or stalls, from the Orient" .)