Crack found on most headstones (3)
I believe the answer is:
rip
'crack' is the definition.
(thesaurus)
'on most headstones' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'most' means to remove the last letter.
'headstones' becomes 'ip' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
're' with its final letter taken away is 'r'.
'r'+'ip'='RIP'
'found' is the link.
Can you help me to learn more?
(Other definitions for rip that I've seen before include "Final hope" , "found on grave?" , "Gash" , "Shred" , "Tearaway" .)