Incomplete bathroom fixture causes one to wait (4)
I believe the answer is:
bide
'one to wait' is the definition.
(I've seen this before)
'incomplete bathroom fixture' is the wordplay.
'incomplete' means to remove the last letter.
'bathroom fixture' becomes 'bidet' (I've seen this before).
'bidet' with its final letter taken away is 'BIDE'.
'causes' acts as a link.
(Other definitions for bide that I've seen before include "Stay (obs.)" , "Remain; await (time)" , "Dwell, stay" , "Tarry" , "Stay in a certain place" .)