Bathroom units replaced in midweek? (2,5)
I believe the answer is:
en suite
'bathroom' is the definition.
(I've seen this before)
'units replaced in midweek?' is the wordplay.
'replaced' indicates anagramming the letters.
'in' indicates putting letters inside.
'midweek?' becomes 'ee'.
'units' with letters rearranged gives 'nsuit'.
'nsuit' going within 'ee' is 'EN SUITE'.
(Other definitions for en suite that I've seen before include "Together by bedroom" , "Like bathrooms next to bedrooms" , "Forming a 22 dn" , "Forming a single unit, like bedroom and bathroom" , "Forming a unit or set" .)