English girl: a railway representative (8)
I believe the answer is:
emissary
'representative' is the definition.
(emissary is a kind of representative)
'english girl a railway' is the wordplay.
'english' becomes 'e' (abbreviation).
'girl' becomes 'miss' (I've seen this before**).
'railway' becomes 'ry' (abbreviation for railway).
'e'+'miss'+'a'+'ry'='EMISSARY'
(Other definitions for emissary that I've seen before include "Government agent" , "I'm sent!" , "Person sent to negotiate" , "Diplomatic agent" , "Diplomatic representative" .)