Large number in factory, one by a road (8)
I believe the answer is:
milliard
'large number' is the definition.
'milliard' can be an answer for 'number' (milliard is a kind of number). I'm not sure about the 'large' bit.
'factory one by a road' is the wordplay.
'factory' becomes 'mill' (mill is a type of factory).
'one' becomes 'i' (Roman numeral).
'by' says to put letters next to each other.
'road' becomes 'rd' (abbreviation).
'mill'+'i'+'a'+'rd'='MILLIARD'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for milliard that I've seen before include "One thousand million" , "Ten to the power nine" , "A huge number" .)