Clever tool for breaking walls closer to joist (4)
I believe the answer is:
cute
'clever' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for cute that I've seen before include "Attractive or ingenious" , "Sweet, attractive" , "Charming, quaint" , "Quaintly pleasing" , "Smart" .)