Bathroom (2,5)
I believe the answer is:
en suite
'bathroom' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for en suite that I've seen before include "Forming a 22 dn" , "Together by bedroom" , "(Of a bedroom) having a private bathroom attached" , "(Of bathroom) immediately adjoining bedroom" , "Forming a unit or set" .)