One plans development of the Arctic (9)
I believe the answer is:
architect
'one plans development' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'of the arctic' is the wordplay.
'of' is an anagram indicator (the answer comes from or 'of' the letters).
'the'+'arctic'='thearctic'
'thearctic' with letters rearranged gives 'ARCHITECT'.
Can you help me to learn more?
(Other definitions for architect that I've seen before include "Designer of buildings" , "professional" , "Perhaps Scott" , "Building designer" , "Author" .)