Ruined city, one where a King was killed and another is buried (7)
I believe the answer is:
memphis
'ruined city' is the definition.
'one where a king was killed and another is buried' is the wordplay.
I cannot really see how this works, but
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is present in the answer.
'was' could be 'is' (being is a kind of being) and 'is' is found within the answer.
This explanation may well be incorrect...
(Other definitions for memphis that I've seen before include "Largest city in Tennessee" , "City of Tennessee/Egypt" , "Ancient Egyptian city" , "US city where Gracelands is located" , "Name of city at different times overlooking the Nile and Mississippi?" .)