Labour maintaining posh empty room causes unrest (7)
I believe the answer is:
turmoil
'unrest' is the definition.
(thesaurus)
'labour maintaining posh empty room' is the wordplay.
'labour' becomes 'toil' (synonyms).
'maintaining' means one lot of letters goes inside another.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-u).
'empty' means to remove the middle letters.
'room' with its middle removed is 'rm'.
'u'+'rm'='urm'
'toil' going around 'urm' is 'TURMOIL'.
'causes' is the link.
(Other definitions for turmoil that I've seen before include "Unrest - upheaval" , "Agitation, confusion" , "Hubbub" , "Sturm und Drang" , "Chaos" .)