It is bound to hold a bone in the right position (6)
I believe the answer is:
splint
'right position' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'it is bound to hold a bone in' is the wordplay.
'it is bound' suggests removing the centre (I've seen 'bounds of' mean this (the letters which form the boundaries of the word)).
'to hold' becomes 'stop' (stop is a kind of hold).
'a bone in' becomes 'lint' (I can't justify this - if you can you should give a lot more credence to this answer).
'stop' with its centre removed is 'sp'.
'sp'+'lint'='SPLINT'
'the' is the link.
Can you help me to learn more?
(Other definitions for splint that I've seen before include "Aid to bone-setting" , "'It's used to immobilise a broken leg, say (6)'" , "Contrivance for holding a broken bone in position" , "Bone setting support" , "Orthopaedic device for immobilising part of the body" .)