Glum little Maureen got out of bed (6)
I believe the answer is:
morose
'glum' is the definition.
(I know that glum can be written as morose)
'little maureen got out of bed' is the wordplay.
'little maureen' becomes 'Mo' (Mo can be short for Maureen).
'got out of bed' becomes 'rose' (rise can mean to get out of bed).
'mo'+'rose'='MOROSE'
(Other definitions for morose that I've seen before include "Silent, gloomy and ill-tempered" , "Sullen and gloomy" , "Sullen or glum." , "Sad" , "Sullen. bad-tempered" .)