Irregularity of arrangement up to now - with millions invested in railway (9)
I believe the answer is:
asymmetry
'irregularity of arrangement' is the definition.
'asymmetry' can be an answer for 'irregularity' (I've seen this before). I'm not sure about the 'of arrangement' bit.
'up to now with millions invested in railway' is the wordplay.
'up to now' becomes 'as yet' (both can mean until the present time).
'with' means one lot of letters goes inside another.
'millions' becomes 'mm' (m is an abbreviation for million).
'invested in railway' becomes 'ry' (I can't justify this - if you can you should believe this answer much more).
'asyet' placed around 'mm' is 'asymmet'.
'asymmet'+'ry'='ASYMMETRY'
Can you help me to learn more?
(Other definitions for asymmetry that I've seen before include "displays a lack of regularity" , "Lack of similarity between two parts or halves" , "with different faces" , "Irregularity" .)