Sibling, menacing, removes nail regularly (6)
I believe the answer is:
sister
'sibling' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for sister that I've seen before include "Senior nurse; relative" , "Resits (anag.)" , "of the same origin" , "Nurse, nun or relation" , "Female relation" .)