A bird's exciting times out (8)
I believe the answer is:
titmouse
'a bird's' is the definition.
(titmouse is a kind of bird)
'exciting times out' is the wordplay.
'exciting' indicates anagramming the letters.
'times'+'out'='timesout'
'timesout' with letters rearranged gives 'TITMOUSE'.
(Other definitions for titmouse that I've seen before include "Small bird" , "Small songbird" .)
I've seen this clue in The Telegraph.
Want a hint initially instead of a full solution?
Install my app