Means to follow campaign for a raised road (8)
I believe the answer is:
causeway
'a raised road' is the definition.
(I've seen this before)
'means to follow campaign' is the wordplay.
'means' becomes 'way' ('way' can be a synonym of 'means').
'to follow' means one lot of letters go next to another.
'campaign' becomes 'cause' ('cause' can be a synonym of 'campaign').
'way' put after 'cause' is 'CAUSEWAY'.
'for' is the link.
(Other definitions for causeway that I've seen before include "Raised road across water - may be a Giant's" , "Raised path over water" , "Raised road across wet area" , "Paved footpath" , "Raised road crossing shallow water" .)