It separates the section one can get into (9)
I believe the answer is:
partition
'it separates the section one can' is the definition.
The definition suggests a singular noun which matches the answer.
'into' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'into' is 'tion' which is within the answer.
The remaining letters 'parti' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'get' is the link.
Can you help me to learn more?
(Other definitions for partition that I've seen before include "Separation (of a country) into separate nations" , "wall" , "Screen" , "Divide; divider" , "segregation" .)