___ headache (5)
'headache' is the definition.
(I know that migraine is a type of headache)
This is all the clue.
(Other definitions for migraine that I've seen before include "Severe recurrent headache" , "Severe recurring headache" , "Throbbing inside the head" , "It brings severe headache" , "may give one a sort of headache" .)
(Other definitions for sinus that I've seen before include "Space in temple" , "Cavity within a bone" , "Cavity in the facial bones" , "Anatomical cavity" , "Air-filled cavity of the skull" .)