Agrees to dig up bone and shell in South Africa (6)
I believe the answer is:
adopts
'agrees' is the definition.
The definition and answer can be both to do with ownership as well as being verbs in their -s form.
Perhaps they are linked in a way I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for adopts that I've seen before include "Takes as one's own, say child" , "Assumes (an attitude)" , "Legally takes on (child)" , "Takes a child into one's family" , "Takes into one's family legally" .)