This might help you see French industrial town (4)
I believe the answer is:
lens
I believe this is a double definition.
'this might help you see' is the first definition.
(eg glasses lenses)
'french industrial town' is the second definition.
(town in northern France)
(Other definitions for lens that I've seen before include "Focussing glass" , "Focusing glass" , "Transparent optical device" , "Part of telescope" , "French city" .)