The scheme is for a start, to cut the stone (9)
I believe the answer is:
stratagem
'the scheme' is the definition.
(stratagem is a kind of scheme)
'a start to cut the stone' is the wordplay.
'to cut' indicates an anagram (cut can mean mixed).
'the stone' becomes 'gem' (I've seen this in another clue).
'a'+'start'='astart'
'astart' is an anagram of 'strata'.
'strata'+'gem'='STRATAGEM'
'is for' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for stratagem that I've seen before include "Ruse" , "Tactic to gain an advantage" , "Device" , "Clever scheme" , "Crafty manoeuvre" .)