Enormous attic in disarray (7)
I believe the answer is:
titanic
'enormous' is the definition.
(I've seen this in another clue)
'attic in disarray' is the wordplay.
'disarray' indicates an anagram.
'attic'+'in'='atticin'
'atticin' is an anagram of 'TITANIC'.
(Other definitions for titanic that I've seen before include "In attic (anag.)" , "Great ocean liner sunk by iceberg" , "Doomed liner found in attic" , "made of metal" , "Ship that sank in 1912" .)