Note about hospital department is something to remember (7)
I believe the answer is:
memento
'something to remember' is the definition.
(something which helps you to remember)
'note about hospital department' is the wordplay.
'note' becomes 'memo' (memo is a kind of note).
'about' is an insertion indicator.
'hospital department' becomes 'ent'.
'memo' enclosing 'ent' is 'MEMENTO'.
'is' acts as a link.
(Other definitions for memento that I've seen before include "Something kept" , "trophy" , "A reminder of death - . . . . . . . mori" , "Object kept as a souvenir" , "Keepsake or souvenir" .)