Being still inebriated after partying and missing bed (7)
I believe the answer is:
inertia
'being still' is the definition.
(inertia is stillness or lack of movement)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for inertia that I've seen before include "Disinclination to respond" , "I retain, being without energy" , "Tendency to remain at rest or in steady motion" , "Slowness to act, lack of strength" , "Change-resisting tendency" .)