One who copies interior of dull hangings (7)
I believe the answer is:
drapery
'dull hangings' is the definition.
'drapery' can be an answer for 'hangings' (I've seen this in another clue). I am not sure about the 'dull' bit.
'one who copies interior' is the wordplay.
'one who' becomes 'dr' (from TV series Doctor Who).
'copies interior' becomes 'apery' (I can't explain this - if you can you should believe this answer much more).
'dr'+'apery'='DRAPERY'
'of' is the link.
Can you help me to learn more?
(Other definitions for drapery that I've seen before include "Curtains and other hangings" , "Fabric hanging in loose folds" , "Bulgaria's eastern border" , "collection of fabrics" , "Cloth goods." .)