Neat tramp messed up rooms (9)
I believe the answer is:
apartment
'rooms' is the definition.
(I've seen this before)
'neat tramp messed up' is the wordplay.
'messed up' indicates an anagram.
'neat'+'tramp'='neattramp'
'neattramp' anagrammed gives 'APARTMENT'.
(Other definitions for apartment that I've seen before include "place to live" , "Accommodation" , "Suite of rooms to live in" , "Set of rooms or American flat" , "19 across" .)