Jewelry box item (3)
I believe the answer is:
'jewelry box item' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pin that I've seen before include "Fastener; skittle" , "Stick with flag placed in golf hole" , "Small object to fasten or attach" , "Debit-card number" , "Peg or nail" .)