Jewellery item — severe reprimand when directions are reversed (6)
I believe the answer is:
locket
'jewellery item' is the definition.
I don't understand how the rest of the clue works.
(Other definitions for locket that I've seen before include "Small ornamental case for photo etc." , "Lucy" , "Picture-case on chain" , "Small ornamental case around the neck" , "Small ornamental case for picture" .)