Batter sections in defensive earthworks (8)
I believe the answer is:
ramparts
'defensive earthworks' is the definition.
(defensive walls)
'batter sections' is the wordplay.
'batter' becomes 'ram' (I've seen this before).
'sections' becomes 'parts' ('part' can be a synonym of 'section').
'ram'+'parts'='RAMPARTS'
'in' is the link.
(Other definitions for ramparts that I've seen before include "Earth banks as fortifications topped with parapets" , "Fortified earth banks topped with parapets" , "Defensive fortifications" , "Defensive walls with parapets" , "Sheep bits for fortifications" .)