Height, elevation (8)
I believe the answer is:
altitude
This clue is a double definition.
'height' is the first definition.
(synonyms)
'elevation' is the second definition.
(I know that elevation can be written as altitude)
(Other definitions for altitude that I've seen before include "Loftiness" , "Elevation above sea-level" , "Angular distance above the horizon" , "Elevation above sea level" , "Height above sea level" .)