Arrive originally by means of railway to see bird enclosure (6)
I believe the answer is:
aviary
'bird enclosure' is the definition.
(an aviary is a large enclosure for birds)
'arrive originally by means of railway' is the wordplay.
'originally' says to take the initial letters.
'by means of' becomes 'via' (via can mean 'by means of' or 'using').
'railway' becomes 'ry' (abbreviation for railway).
The first letter of 'arrive' is 'a'.
'a'+'via'+'ry'='AVIARY'
'to see' acts as a link.
(Other definitions for aviary that I've seen before include "Collection of birds" , "Building for keeping birds" , "Where flights are limited" , "Bird sanctuary" , "Large enclosure for birds" .)