An artist's sharp-ended tool (4)
I believe the answer is:
rasp
'tool' is the definition.
(rasp is a kind of tool)
'an artist's sharp-ended' is the wordplay.
'an artist's' becomes 'RAs' (Royal Academician, member of Royal Academy of Arts).
'sharp ended' becomes 'p' (I can't explain this - if you can you should give a lot more credence to this answer).
'ras'+'p'='RASP'
Can you help me to learn more?
(Other definitions for rasp that I've seen before include "sort of berry?" , "unpleasant noise" , "Harsh noise - file" , "File - berry" , "Harsh grating sound" .)