Religious person giving description of our earthy sphere (6)
I believe the answer is:
oblate
I believe this is a double definition.
'religious person' is the first definition.
(someone dedicated to a religious life)
'description of our earthy sphere' is the second definition.
(the Earth is an oblate spheroid)
'giving' is the link.
(Other definitions for oblate that I've seen before include "a religious person" , "Of spheroid, flattened at the ends" , "Of sphere, flattened at poles" , "person who's dedicated" , "One dedicated to monastic life" .)