Songbird circling large quail (6)
I believe the answer is:
flinch
'quail' is the definition.
(both can mean to show fear)
'songbird circling large' is the wordplay.
'songbird' becomes 'finch' (type of songbird).
'circling' means one lot of letters goes inside another (circling can mean going around or containing).
'large' becomes 'L' (eg in clothes sizes).
'finch' placed around 'l' is 'FLINCH'.
(Other definitions for flinch that I've seen before include "Shrink back with fear" , "Draw back in fear, recoil" , "Recoil, shrink back" , "Draw back in shock" , "quail?" .)