Material in bathroom in short supply? (5)
I believe the answer is:
toile
'material' is the definition.
(type of fabric)
'bathroom in short supply?' is the wordplay.
'bathroom' becomes 'toilet' ('toilet' can be a synonym of 'bathroom').
'in short supply?' means to remove the last letter (I've seen 'in short supply' mean this).
'toilet' with its final letter removed is 'TOILE'.
'in' acts as a link.
(Other definitions for toile that I've seen before include "cloth" , "cheap prototype" , "dress material" , "6 [LINEN]" , "Fabric" .)