Copy doctor opening curtain (5)
I believe the answer is:
drape
'curtain' is the definition.
(I know that curtain can be written as drape)
'copy doctor opening' is the wordplay.
'copy' becomes 'ape' (ape can mean to copy or imitate).
'doctor' becomes 'Dr' (abbreviation).
'opening' means one lot of letters go next to another (some letters appear before or \'open\' others).
'ape' put after 'dr' is 'DRAPE'.
(Other definitions for drape that I've seen before include "Loose fabric cover" , "Hang - curtain" , "Hang (cloth) in folds (on something)" , "Swathe" , "Cover loosely for padre" .)