Stone containing aluminium compound (4)
I believe the answer is:
salt
'compound' is the definition.
(salt is a kind of compound)
'stone containing aluminium' is the wordplay.
'stone' becomes 'st' (abbreviation).
'containing' is an insertion indicator.
'aluminium' becomes 'al' (Al is the chemical symbol for aluminium).
'st' enclosing 'al' is 'SALT'.
(Other definitions for salt that I've seen before include "Pile up" , "NaCl" , "White crystalline substance" , "Liveliness" , "Seasoning; old sailor" .)