Bird in queue behind rail (7)
I believe the answer is:
sparrow
'bird' is the definition.
(sparrow is a kind of bird)
'queue behind rail' is the wordplay.
'queue' becomes 'row'.
'behind' means one lot of letters go next to another.
'rail' becomes 'spar' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'row' put after 'spar' is 'SPARROW'.
'in' is the link.
Can you help me to learn more?
(Other definitions for sparrow that I've seen before include "Winger" , "Bird with cockney associations" , "Pirate" , "Common town bird" , "(Formerly very) common British bird" .)