Mock medico opening curtain (5)
I believe the answer is:
drape
'curtain' is the definition.
(I know that curtain can be written as drape)
'mock medico opening' is the wordplay.
'mock' becomes 'ape' (aping is a kind of mocking).
'medico' becomes 'Dr' (synonyms).
'opening' says to put letters next to each other (some letters appear before or 'open' others).
'ape' after 'dr' is 'DRAPE'.
(Other definitions for drape that I've seen before include "Swathe" , "Cover loosely for padre" , "Hang (cloth) loosely" , "Cover loosely with cloth" , "Pared (anag.)" .)