Shy going to bed (8)
I believe the answer is:
retiring
I believe this is a double definition.
'shy' is the first definition.
(I've seen this before)
'going to bed' is the second definition.
('retire' can be a synonym of 'go to bed')
(Other definitions for retiring that I've seen before include "Shunning contact with others" , "Shy; stopping work" , "shrinking" , "Reluctant to draw attention to oneself" , "going up the stairs?" .)