Leave maid to work, being old-fashioned! (9)
I believe the answer is:
mediaeval
'old-fashioned' is the definition.
(I've seen this before)
'leave maid to work' is the wordplay.
'to work' indicates anagramming the letters.
'leave'+'maid'='leavemaid'
'leavemaid' with letters rearranged gives 'MEDIAEVAL'.
'being' is the link.
(Other definitions for mediaeval that I've seen before include "out of the Dark Ages" , "Old-fashioned" .)