Hot stuff from Sun involved in slanderous attack (7)
I believe the answer is:
mustard
'hot stuff' is the definition.
'sun involved in slanderous attack' is the wordplay.
'sun' becomes 'star' (I've seen this before).
'involved in' means one lot of letters goes inside another.
'slanderous attack' becomes 'mud' (as in dragging someone's name through the mud).
'star' placed inside 'mud' is 'MUSTARD'.
'from' is the link.
(Other definitions for mustard that I've seen before include "Powdered seeds used to make condiment" , "Standard of keenness" , "Dark yellow" , "Plant" , "Yellow paste as condiment - very keen" .)