Range analysed, naturally dropping back somewhat (5)
I believe the answer is:
andes
'range' is the definition.
(South American mountain range)
'analysed naturally dropping back somewhat' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'back' says the letters should be written in reverse.
'sedna' is hidden within 'analysed naturally dropping'.
'sedna' written backwards gives 'ANDES'.
(Other definitions for andes that I've seen before include "Mounts" , "Mountains in west" , "danes found in mountains" , "Aconcagua the highest in this range" , "South American mountains" .)