Curling regularly pared part of a bone (5)
I believe the answer is:
ulnar
'of a bone' is the definition.
(relating to the ulna, an arm bone)
'curling regularly pared part' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'pared' indicates the central letters (pare or remove edges from the word).
The centre of 'part' is 'ar'.
The alternating letters of 'curling' are 'uln'.
'uln'+'ar'='ULNAR'
(Other definitions for ulnar that I've seen before include "Relating to one of the bones of the forearm" , "of certain bones" , "Relating to a bone in the forearm" , "Relating to a particular arm bone" .)