A cellar used for humiliation (9)
I believe the answer is:
abasement
'for humiliation' is the definition.
(abasement is a kind of humiliation)
'a cellar' is the wordplay.
'cellar' becomes 'basement' (both can mean the space underneath a house).
'a'+'basement'='ABASEMENT'
'used' is the link.
(Other definitions for abasement that I've seen before include "Humiliating situation" , "will humiliate us" , "Degradation" , "demeaning" , "Crawling" .)