Baño feature (5)
I believe the answer is:
tilde
'bano feature' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tilde that I've seen before include "Spanish cedilla" , "Squiggle over Spanish n" , "Spanish accent sign" , "Mark, sometimes on keyboards" , "Wavy line in Spanish" .)