Great deal of stone (3)
I believe the answer is:
ton
'great deal' is the definition.
'of stone' is the wordplay.
'of' says the answer is hidden in the clue.
'TON' can be found hidden inside 'stone'.
(Other definitions for ton that I've seen before include "100 mph, runs, etc" , "Fashionable" , "Imperial unit of weight" , "Style" , "Heavyweight" .)