Deft backing for Siberia's top fur (5)
I believe the answer is:
sable
'top fur' is the definition.
'sable' can be an answer for 'fur' (sable is a kind of fur). I am not sure about the 'top' bit.
'deft backing for siberia's' is the wordplay.
'deft' becomes 'able' (I've seen this in another clue).
'backing' says to put letters next to each other.
'for siberia' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'able' put after 's' is 'SABLE'.
Can you help me to learn more?
(Other definitions for sable that I've seen before include "Bales (anag.)" , "Bales of valuable Russian fur" , "Type of fur" , "fur coat" , "Black; antelope" .)