Drill giving you headache? (4)
I believe the answer is:
bore
I believe this is a double definition.
'drill' is the first definition.
(I know that drill can be written as bore)
'headache?' is the second definition.
(thesaurus)
'giving you' is the link.
(Other definitions for bore that I've seen before include "Dull person; use a drill" , "Carried - drill" , "Irritate" , "Drill - pest" , "Wearisome person" .)