Nudist worked on railway business (8)
I believe the answer is:
industry
'business' is the definition.
(industry is a kind of business)
'nudist worked on railway' is the wordplay.
'worked' is an anagram indicator.
'on' means one lot of letters go next to another.
'railway' becomes 'ry' (abbreviation for railway).
'nudist' with letters rearranged gives 'indust'.
'indust'+'ry'='INDUSTRY'
(Other definitions for industry that I've seen before include "Commercial enterprise, the making of goods, say" , "Manufacturing enterprises" , "Steady application - to manufacturing?" , "Commerce" , "Business" .)