The French find Virginia hot stuff (4)
I believe the answer is:
lava
'hot stuff' is the definition.
(I've seen this in another clue)
'the french find virginia' is the wordplay.
'the french' becomes 'la' (one of the French words for 'the').
'find' says to put letters next to each other.
'virginia' becomes 'va' (US state abbreviation).
'la'+'va'='LAVA'
(Other definitions for lava that I've seen before include "Flowing volcanic matter" , "Volcanic outflow" , "Volcanic emission" , "Volcanic outpouring" , "Flowing extrusive magma" .)