Fortifications (8)
'fortifications' is the definition.
(rampart is a kind of fortification)
This is all the clue.
(Other definitions for ramparts that I've seen before include "Earth banks as fortifications topped with parapets" , "used defensively" , "Defensive walling" , "Sheep bits for fortifications" , "Fortified earth banks topped with parapets" .)
(Other definitions for defences that I've seen before include "Means of protection" , "barricades" , "Protections or justifications" , "legal cases for those charged" , "ramparts?" .)