Last stone carved with direct message in it (7)
I believe the answer is:
endmost
'last' is the definition.
(similar in meaning)
'stone carved with direct message in it' is the wordplay.
'carved' indicates anagramming the letters.
'with direct message' becomes 'dm' (I can't explain this - if you can you should give a lot more credence to this answer).
'in it' is an insertion indicator.
'stone' anagrammed gives 'enost'.
'enost' going around 'dm' is 'ENDMOST'.
Can you help me to learn more?
(Other definitions for endmost that I've seen before include "Last in the line" , "Farthest" , "Most distant" , "Last in a row" , "extreme situation" .)