Rinse out small warning devices (6)
I believe the answer is:
sirens
'warning devices' is the definition.
(I've seen this in another clue)
'rinse out small' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'small' becomes 's' (abbreviation - e.g. clothes size).
'rinse' with letters rearranged gives 'siren'.
'siren'+'s'='SIRENS'
(Other definitions for sirens that I've seen before include "Loud warning signals" , "Devices that warn with a loud wailing noise" , "Warning devices with loud wailing noise" , "Alluring women" , "Sea nymphs" .)