Going back to bed (8)
I believe the answer is:
retiring
'going' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I can't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for retiring that I've seen before include "Giving up work for good" , "Shy and fond of being on one's own" , "Shy, avoiding company" , "Diffident" , "Reluctant to draw attention to oneself" .)