Headache tablet (7)
I believe the answer is:
'headache tablet' is the definition.
'aspirin' can be an answer for 'tablet' (tablet of aspirin medication). I also know that 'headache' relates to this answer.
This is the entire clue.
(Other definitions for aspirin that I've seen before include "Common analgesic drug" , "headache cure" , "Headache pill" , "Synthetic analgesic" , "Anti-inflammatory analgesic" .)