Miss mostly seen round copper's place (5)
I believe the answer is:
locus
'place' is the definition.
('place' in Latin)
'miss mostly seen round copper's' is the wordplay.
'miss mostly' becomes 'los' (I can't explain this - if you can you should give a lot more credence to this answer).
'seen round' indicates putting letters inside.
'copper' becomes 'cu' (chemical symbol).
'los' enclosing 'cu' is 'LOCUS'.
Can you help me to learn more?
(Other definitions for locus that I've seen before include "Spot" , "Particular point" , "Venue" , "Particular position (of something)" , "Position, point, place" .)