Drilled (5)
I believe the answer is:
bored
'drilled' is the definition.
('bore' can be a synonym of 'drill')
This is the entire clue.
(Other definitions for bored that I've seen before include "Drilled; wearied" , "Drilled (a hole)" , "Suffering from ennui" , "Tired and uninterested" , "Unstimulated" .)