Care about land measurement (4)
I believe the answer is:
Here is my best explanation:
'land measurement' is the definition.
(I've seen this before)
'care about' is the subsidiary indication.
'about' indicates an anagram.
'care' with letters rearranged gives 'acre'.
(Other definitions for acre that I've seen before include "Measure of land area", "once occupied by Crusaders", "Imperial area", "Port", "Old unit of area - old port", "Land area", "Unit of area of 4,840 square yards", "Levant sea port", "point four nought five of a hectare" and "Middle East port".)