Bird lives in hide (6)
I believe the answer is:
siskin
'bird' is the definition.
(siskin is a kind of bird)
'lives in hide' is the wordplay.
'lives' becomes 'is' ('be' can be a synonym of 'live').
'in' means one lot of letters goes inside another.
'hide' becomes 'skin' ('skin' can be a synonym of 'hide'**).
'is' going into 'skin' is 'SISKIN'.
(Other definitions for siskin that I've seen before include "Type of bird" , "Greenish songbird related to Goldfinch" , "Breed of finch" , "Small songbird related to the goldfinch" , "Type of finch" .)