Dirt about celebrity is hot stuff! (7)
I believe the answer is:
mustard
'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' (a star is a celebrity or famous person).
'mud' enclosing 'star' is 'MUSTARD'.
'is' is the link.
(Other definitions for mustard that I've seen before include "Byword for keenness" , "Pungent condiment" , "See 2" , "Type of Brassica" , "leading performer in wet conditions" .)