Soldiers with child seen by railway (8)
I believe the answer is:
infantry
'soldiers' is the definition.
(I've seen this before)
'child seen by railway' is the wordplay.
'child' becomes 'infant' (infant is a kind of child).
'seen by' is a charade indicator (letters next to each other).
'railway' becomes 'ry' (abbreviation for railway).
'infant'+'ry'='INFANTRY'
'with' is the link.
(Other definitions for infantry that I've seen before include "fighting group" , "Army unit of foot soldiers" , "Grunts" , "part of the army" , "Foot-soldiers" .)