Science of Earth measurement (7)
I believe the answer is:
geodesy
'science of earth measurement' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for geodesy that I've seen before include "earth measurement" , "surveying the earth" , "Earth measurements on a large scale" , "Scientific study of world's shape and size" , "Extensive survey" .)