Remark about role in section (11)
I believe the answer is:
compartment
'section' is the definition.
(I have seen 'Separate section ' mean 'compartment' so perhaps 'section' could also mean 'compartment')
'remark about role' is the wordplay.
'remark' becomes 'comment' (commenting is a kind of remarking**).
'about' is an insertion indicator.
'role' becomes 'part' ('part' can be a synonym of 'role').
'comment' going around 'part' is 'COMPARTMENT'.
'in' is the link.
(Other definitions for compartment that I've seen before include "one of many coach may have" , "Box" , "cubicle" , "Section of railway carriage etc" , "part of carriage" .)