Look right by railway truck (5)
I believe the answer is:
lorry
'truck' is the definition.
(lorry is a kind of truck)
'look right by railway' is the wordplay.
'look' becomes 'lo'.
'right' becomes 'r' (common abbreviation).
'by' means one lot of letters go next to another.
'railway' becomes 'ry' (abbreviation for railway**).
'lo'+'r'+'ry'='LORRY'
(Other definitions for lorry that I've seen before include "Load-carrying vehicle" , "From which stolen goods fall?" , "Large motor vehicle for transporting goods" , "Transport vehicle" , "Commercial vehicle" .)