Nasal partition (6)
I believe the answer is:
septum
'nasal partition' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for septum that I've seen before include "Partition between two chambers" , "Partition in nose between nostrils" , "Dividing partition between the nostrils" , "Partition between two cavities of the nose" , "Division between nostrils" .)