Wash out broken siren (5)
I believe the answer is:
rinse
'wash out' is the definition.
(I've seen this before)
'broken siren' is the wordplay.
'broken' indicates an anagram.
'siren' anagrammed gives 'RINSE'.
(Other definitions for rinse that I've seen before include "Use water to remove soap" , "Run water through" , "Wash lightly without soap" , "Colour" , "Wash off surface dirt" .)