One piece of jewellery or two permitted (8)
I believe the answer is:
bracelet
'one piece of jewellery' is the definition.
(bracelet is a type of jewellery item)
'two permitted' is the wordplay.
'two' becomes 'brace' (brace is a kind of two).
'permitted' becomes 'let' (to let something happen is to permit it).
'brace'+'let'='BRACELET'
'or' is the link.
(Other definitions for bracelet that I've seen before include "Might Bel react to the piece of jewellery?" , "Jewellery worn around the wrist" , "charm?" , "Ornament - handcuff (slang)" , "Wrist, arm adornment" .)