Stone smashed in grate (7)
I believe the answer is:
granite
'stone' is the definition.
(I know that granite is a type of batholite)
'smashed in grate' is the wordplay.
'smashed' indicates an anagram.
'in'+'grate'='ingrate'
'ingrate' is an anagram of 'GRANITE'.
(Other definitions for granite that I've seen before include "Get rain (anag) - rock" , "Crystalline rock" , "Very hard type of rock" , "Showing great resolution" , "Tangier (anag.)" .)