Part of a rosary (4)
I believe the answer is:
bead
'part of a rosary' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bead that I've seen before include "Round piece of glass, etc" , "Small ball with a hole through the middle" , "Drop, part of rosary" , "Small drop of moisture" , "bit off necklace, say" .)