Artist finally sculpted two bones (5)
I believe the answer is:
radii
'bones' is the definition.
(radius is a kind of bone)
'artist finally sculpted two' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'finally' indicates one should take the final letters.
'two' becomes 'II' (roman numeral).
The last letter of 'sculpted' is 'd'.
'ra'+'d'+'ii'='RADII'
(Other definitions for radii that I've seen before include "They meet in the middle of a circle" , "Two making up diameter" , "Straight lines from the centre to the surface of a sphere" , "Spokes of a circle" , "Spokes of wheel - bones of arm" .)