Making holes is not interesting (6)
I believe the answer is:
boring
I believe this is a double definition.
'making holes' is the first definition.
(I've seen this before)
'not interesting' is the second definition.
('bore' is the opposite to 'interest')
'is' acts as a link.
(Other definitions for boring that I've seen before include "Tedious, of no interest" , "Making holes" , "Dull and repetitive, a turn-off" , "Tedious and tiring" , "Drilling - it's monotonous" .)