Inferior, so joint bottom? (6)
I believe the answer is:
coarse
'inferior' is the definition.
(similar in meaning)
'joint bottom?' is the wordplay.
'joint' becomes 'co' (I've seen this in other clues).
'bottom?' becomes 'arse' (synonyms).
'co'+'arse'='COARSE'
'so' is the link.
(Other definitions for coarse that I've seen before include "Rough or crude, lacking refinement" , "Rough to the touch or lacking refinement" , "Vulgar - unrefined" , "Rough in texture or crude in manner" , "Rough or rude" .)