Restorative note (5)
I believe the answer is:
tonic
I believe this is a double definition.
'restorative' is the first definition.
('tonic' can be a synonym of 'restorative')
'note' is the second definition.
(tonic is a kind of note)
(Other definitions for tonic that I've seen before include "Invigorating medicine - keynote" , "Fillip" , "do for musicians" , "Keynote of a scale" , "Invigorating drink" .)