Unpleasant; of poor quality (6)
I believe the answer is:
grotty
I believe this clue is a double definition.
'unpleasant' is the first definition.
(synonyms)
'of poor quality' is the second definition.
(I've seen this before)
(Other definitions for grotty that I've seen before include "Ugly - dirty - ill" , "Of poor quality" , "Unpleasant; ill" , "rough" , "Unwell (slang) - unpleasant (slang)" .)