Just the sort of necklace for a girl (5)
I believe the answer is:
pearl
'girl' is the definition.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for pearl that I've seen before include "Off-white colour" , "Highly-valued thing" , "Lustrous structure in a mollusc shell" , "Small type" , "Paragon" .)