Going to bed, shrinking (8)
I believe the answer is:
retiring
I believe this is a double definition.
'going to bed' is the first definition.
('retire' can be a synonym of 'go to bed')
'shrinking' is the second definition.
(I've seen this before)
(Other definitions for retiring that I've seen before include "taking clothes off etc?" , "Shunning contact with others" , "Quiet" , "Stopping work permanently" , "Shy, avoiding company" .)