Line a certain area (8)
I believe the answer is:
district
'area' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for district that I've seen before include "Area of town or country" , "Zone, area" , "Area of town/country" , "Area, region" , "Territorial division" .)