Notes appeal for help (3)
I believe the answer is:
sos
I believe this is a double definition.
'notes' is the first definition.
(more than one so, a musical note)
'appeal for help' is the second definition.
(I've seen this before)
(Other definitions for sos that I've seen before include "Distress call" , "Help with dots and dashes" , "Appeal for help" , "International distress code" , "urgent appeal" .)