Dirt about celebrity — some hot stuff (7)
I believe the answer is:
mustard
'some hot stuff' is the definition.
'dirt about celebrity' is the wordplay.
'dirt' becomes 'mud' (mud is a kind of dirt).
'about' is an insertion indicator.
'celebrity' becomes 'star' (I've seen this before).
'mud' enclosing 'star' is 'MUSTARD'.
(Other definitions for mustard that I've seen before include "Proverbially keen condiment" , "It gives a bit of a kick" , "The keen stuff ?" , "Powdered seeds used to make condiment" , "Colonel sometimes suspected" .)