Kneecaps (8)
I believe the answer is:
patellae
'kneecaps' is the definition.
('patella' can be a synonym of 'kneecap')
This is all the clue.
(Other definitions for patellae that I've seen before include "Bony bits" , "The formal kneecaps" , "Late leap twisted kneecaps" , "Bones" .)