Rinse out warning device (5)
I believe the answer is:
Here is my best explanation:
'warning device' is the definition.
(I've seen this before)
'rinse out' is the subsidiary indication.
'out' is an anagram indicator.
'rinse' with letters rearranged gives 'siren'.
(Other definitions for siren that I've seen before include "Alluring woman; warning", "Attractive lady", "Hooter - dangerous woman?", "Alluring female", "Loud whistle or dangerous woman", "Temptress - warning device", "Warning at sea", "Warning signal generator", "Loud whistle or kind of witch" and "Temptress; warning signal".)