Animals in bush are silent (5)
I believe the answer is:
hares
'animals' is the definition.
(I have seen 'Swift animals ' mean 'hares' so perhaps 'animals' could also mean 'hares')
'in bush are silent' is the wordplay.
'in' says the answer is hidden in the clue.
'HARES' can be found hidden inside 'bush are silent'.
(Other definitions for hares that I've seen before include "Fleet-footed animals" , "Share of wild animals" , "Rabbit-like creatures" , "Fast animals" , "Long-eared animals" .)