Sullen, bad-tempered (6)
I believe the answer is:
morose
I believe this clue is a double definition.
'sullen' is the first definition.
(both mean miserable)
'bad-tempered' is the second definition.
(morose means sad or in a bad mood)
(Other definitions for morose that I've seen before include "grouchy" , "Surly and unforthcoming" , "Sullen and ill-tempered" , "Sullen and gloomy" , "in a grumpy mood" .)