Coin, rare, placed in the middle (7)
I believe the answer is:
centred
'placed in the middle' is the definition.
(I've seen this before)
'coin rare' is the wordplay.
'coin' becomes 'cent' (cent is a kind of coin).
'rare' becomes 'red' (I can't justify this - if you can you should give a lot more credence to this answer).
'cent'+'red'='CENTRED'
Can you help me to learn more?
(Other definitions for centred that I've seen before include "Moved to the middle" , "half way across?" , "Placed in the middle" , "Positioned centrally" .)