Evil intent at shopping centre knocking off fifty diamonds (6)
I believe the answer is:
'evil intent' is the definition.
(I've seen this before)
'knocking off fifty diamonds' is the wordplay.
'knocking' says the letters should be written in reverse.
'off fifty' becomes 'lam' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'diamonds' becomes 'ice' (slang term for diamonds).
'lam' written backwards gives 'mal'.
'at shopping centre' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for malice that I've seen before include "Spiteful, animosity, sometimes a forethought", "Wrongful intention", "Spitefulness", "Spite, venom", "Ill will, a desire to harm others".)