Empty sauce bottles smell cleaner (6)
I believe the answer is:
sponge
'cleaner' is the definition.
'empty sauce bottles smell' is the wordplay.
'empty' means to remove the middle letters.
'bottles' is an insertion indicator (bottle can mean to contain).
'smell' becomes 'pong' (pong can informally mean a bad smell).
'sauce' with its centre removed is 'se'.
'se' enclosing 'pong' is 'SPONGE'.
(Other definitions for sponge that I've seen before include "Porous fibres for soaking up" , "Marine creature - cadge" , "Heavy drinker" , "clean with damp cloth" , "Aquatic creature; cake" .)