Bunk with corner bath (7)
I believe the answer is:
hogwash
'bunk' is the definition.
(I know that bunk can be written as hogwash)
'with corner bath' is the wordplay.
'with' is a charade indicator (letters next to each other).
'corner' becomes 'hog' (I've seen this in other clues).
'bath' becomes 'wash' (I've seen this before).
'hog'+'wash' is 'HOGWASH'.
(Other definitions for hogwash that I've seen before include "Pigswill - nonsense!" , "Colloquial nonsense to pig cleanser" , "Baloney" , "bull" , "Pig food" .)