Be getting on motorway over part of England to make fortune (9)
I believe the answer is:
megabucks
'fortune' is the definition.
'be getting on motorway over part of england' is the wordplay.
'be getting on' becomes 'age'.
'motorway' becomes 'm'.
'over' says the letters should be written backwards.
'part of england' becomes 'bucks' (abbreviation for Buckinghamshire).
'age'+'m'='agem'
'agem' reversed gives 'mega'.
'mega'+'bucks'='MEGABUCKS'
'to make' acts as a link.
(Other definitions for megabucks that I've seen before include "large sum of money" , "Loads of money" , "Vast sums of money" , "Huge money" , "A fortune!" .)