The way on from Rouen (3)
I believe the answer is:
rue
'the way' is the definition.
(I have seen 'French way' mean 'rue' so perhaps 'way' could also mean 'rue')
'on from rouen' is the wordplay.
'from' is a deletion indicator.
'rouen' with 'on' taken away is 'RUE'.
(Other definitions for rue that I've seen before include "Bitter-tasting herb" , "Wish not to have been" , "Repentant sort of shrub?" , "The 'herb of grace'" , "Feel bad" .)