Making holes is not at all interesting (6)
I believe the answer is:
boring
'making holes' is the definition.
(I've seen this before)
'not at all interesting' is the wordplay.
I cannot quite see how this works, but
'not' could be 'o' (I've seen this in other clues) and 'o' is found within the answer.
'at' could be 'in' (synonymous in some cases - eg at school, in school) and 'in' is found within the answer.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for boring that I've seen before include "Tedious, of no interest" , "Mentally wearying" , "Dull and repetitive, a turn-off" , "Drilling - it's monotonous" , "flat" .)