Boring material? (5)
I believe the answer is:
drill
I believe this is a double definition.
'boring' is the first definition.
(I've seen this before)
'material?' is the second definition.
(I've seen this before)
(Other definitions for drill that I've seen before include "Routine" , "Tool; fabric; bore" , "Mollusc that preys on oysters" , "Twill-weave cotton cloth" , "School" .)