Some track bird (4)
I believe the answer is:
rail
This clue is a double definition.
'some track' is the first definition.
('rail' can be a synonym of 'track')
'bird' is the second definition.
(rail is a kind of bird)
(Other definitions for rail that I've seen before include "Supported bar - inveigh" , "Length of track" , "Line" , "Scoff" , "Form of transport" .)