Forearm bone (4)
'forearm bone' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ulna that I've seen before include "Thinner of two long bones in forearm" , "a section of framework" , "Long bone in the arm" , "One of two bones of the forearm" , "The longer and inner bone in forearm" .)
'forearm bone' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for radius that I've seen before include "Straight line from circle's centre to circumference" , "Centre-circumference length" , "Straight line from centre to perimeter of a circle" , "Part of build-up of arms" , "Outer arm bone" .)