Mother left with diamonds, creating animosity (6)
I believe the answer is:
malice
'animosity' is the definition.
(thesaurus)
'mother left with diamonds' is the wordplay.
'mother' becomes 'ma' (ma is a kind of mother).
'left' becomes 'l' (common abbreviation).
'with' says to put letters next to each other.
'diamonds' becomes 'ice' (I've seen this before).
'ma'+'l'+'ice'='MALICE'
'creating' is the link.
(Other definitions for malice that I've seen before include "Ill will, a desire to harm others" , "Spite - desire to hurt" , "Malevolence, spite" , "Spiteful, animosity, sometimes a forethought" , "Spite or spleen, perhaps aforethought" .)