Coy going to bed (8)
I believe the answer is:
Here is my best explanation:
This clue is a double definition.
'coy' is the first definition.
'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 "Timid", "Giving up work for good", "Shy and fond of being on one's own", "Shy - finishing job", "Stopping work permanently", "Reserved", "Diffident", "Giving up work permanently", "Leaving work - shy" and "Shy; stopping work".)