Chief's approach that shows where one is lying (9)
I believe the answer is:
headstone
'where one is lying' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'chief's approach' is the wordplay.
'chief's' becomes 'head's' ('head' can be a synonym of 'chief').
'approach' becomes 'tone' (I can't explain this - if you can you should give a lot more credence to this answer).
'heads'+'tone'='HEADSTONE'
'that shows' is the link.
Can you help me to learn more?
(Other definitions for headstone that I've seen before include "Grave marker" , "It is set up on a grave with inscriptions" , "Memorial on a grave" , "It marks a grave" , "Graveyard slab" .)