Splitting has damaged jewellery item (7)
I believe the answer is:
sharing
'splitting' is the definition.
(thesaurus)
'has damaged jewellery item' is the wordplay.
'damaged' indicates anagramming the letters.
'jewellery item' becomes 'ring' (I've seen this before).
'has' is an anagram of 'sha'.
'sha'+'ring'='SHARING'
(Other definitions for sharing that I've seen before include "Possessing in common" , "Apportioning" .)