Copies given to doctor -- that's curtains! (6)
I believe the answer is:
drapes
'curtains' is the definition.
('drape' can be a synonym of 'curtain')
'copies given to doctor' is the wordplay.
'copies' becomes 'apes' ('ape' can be a synonym of 'copy').
'given to' says to put letters next to each other.
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'apes' put after 'dr' is 'DRAPES'.
'that's' is the link.
(Other definitions for drapes that I've seen before include "Long curtains" , "Hangs (cloth) loosely" , "screens in Windows" , "Spread (anag)" , "Spread like curtains" .)