Bird’s time for sleep, buffeted by wind? (11)
I believe the answer is:
nightingale
'bird's' is the definition.
(nightingale is a kind of bird)
'time for sleep buffeted by wind?' is the wordplay.
'time for sleep' becomes 'night'.
'buffeted by' becomes 'in' (I can't justify this - if you can you should give a lot more credence to this answer).
'wind?' becomes 'gale' (gale is a kind of wind).
'night'+'in'+'gale'='NIGHTINGALE'
(Other definitions for nightingale that I've seen before include "One singing sweetly after dark" , "The Lady with the Lamp, d. 1910" , "Flier" , "Noted songbird" , "Subject of 11 [ODE]" .)