Unfinished tomb in stone compound (9)
I believe the answer is:
aggravate
'compound' is the definition.
(I've seen this before)
'unfinished tomb in stone' is the wordplay.
'unfinished' means to remove the last letter.
'tomb' becomes 'grave' (synonyms).
'in' indicates putting letters inside.
'stone' becomes 'agate' (I've seen this before).
'grave' with its final letter taken away is 'grav'.
'grav' put inside 'agate' is 'AGGRAVATE'.
(Other definitions for aggravate that I've seen before include "Make a bad situation worse" , "Worsen" , "Exasperate or exacerbate" , "Make more serious" , "Annoy; make worse" .)