Bird's unfinished drink placed on railway (5)
I believe the answer is:
ouzel
'bird's' is the definition.
(ouzel is a kind of bird)
'unfinished drink placed on railway' is the wordplay.
I cannot really see how this works, but
'railway' could be 'el' (El train, short for elevated railway) and 'el' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ouzel that I've seen before include "Dipper or blackbird" , "Common black European thrush" .)