Medicated tablet (7)
I believe the answer is:
lozenge
'medicated tablet' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lozenge that I've seen before include "Pastille; rhombus" , "Medicinal tablet" , "Diamond shape; throat sweet" , "Throat pill; diamond" , "Diamond-shaped sweet" .)