Expert in copper and iodine backing polar region (6)
I believe the answer is:
icecap
'polar region' is the definition.
(I've seen this before)
'expert in copper and iodine' is the wordplay.
'expert in' becomes 'ceca' (I am not sure about this - if you are sure you should believe this answer much more).
'copper' becomes 'p'.
'and' says to put letters next to each other.
'iodine' becomes 'I' (chemical symbol).
'ceca'+'p'='cecap'
'cecap' put after 'i' is 'ICECAP'.
'backing' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for icecap that I've seen before include "Cold polar region" , "is always frozen" , "what's on mountain peak?" , "frozen peak" , "Frozen top of mountain etc" .)