Flight of geese identified by European in hide (5)
I believe the answer is:
skein
'flight of geese' is the definition.
(skein can mean a flock of geese)
'european in hide' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'in' is an insertion indicator.
'hide' becomes 'skin' (a hide is an animal skin).
'e' going within 'skin' is 'SKEIN'.
'identified by' acts as a link.
(Other definitions for skein that I've seen before include "flock in flight" , "Loosely coiled length of thread" , "Coil of wool - flock of geese" , "Hank" , "Flight of birds" .)