Notes on role, intended not to have a division (10)
I believe the answer is:
department
'division' is the definition.
(department is a kind of division)
'notes on role intended not to have a' is the wordplay.
'notes' becomes 'de' (two musical notes).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'role' becomes 'part' (eg a part or role in a film).
'intended' becomes 'meant' (to mean something is to intend it).
'not to have' indicates named letters should be taken away.
'meant' with 'a' taken out is 'ment'.
'de'+'part'+'ment'='DEPARTMENT'
(Other definitions for department that I've seen before include "group of civil servants" , "Division of company" , "Ministry" , "Sector" , "Moselle, perhaps" .)