Go down to a bathroom feature (4)
I believe the answer is:
sink
'go down' is the definition.
(I know that sink is a more specific form of go down)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for sink that I've seen before include "Basin for washing up etc" , "Washbasin" , "Pocket (billiards)" , "Descend to a lower level" , "Dip" .)