Curtains spread apart (6)
I believe the answer is:
drapes
'curtains' is the definition.
('drape' can be a synonym of 'curtain')
'spread apart' is the wordplay.
'apart' indicates an anagram (the word is broken apart).
'spread' is an anagram of 'DRAPES'.
(Other definitions for drapes that I've seen before include "Curtains for padres" , "screens in Windows" , "Hangs (cloth) loosely" , "Long curtains" , "Spread (anag)" .)