Wrong to snatch a jewellery item (7)
I believe the answer is:
earring
'jewellery item' is the definition.
(I've seen this before)
'wrong to snatch a' is the wordplay.
'wrong' becomes 'erring' (doing wrong).
'to snatch' indicates putting letters inside (inserted letters are snatched or taken).
'erring' going around 'a' is 'EARRING'.
(Other definitions for earring that I've seen before include "Otic adornment" , "Ornament on lobe" , "Dangly ornament" , "Stud, perhaps, or a drop?" , "Aural pendant" .)