Sinking signal (3)
I believe the answer is:
sos
(Other definitions for sos that I've seen before include "Emergency message" , "Call for help" , "Help initially, Mr Morse" , "Morse Code for help" , "Help code in 13 Across" .)
I believe the answer is:
sos
(Other definitions for sos that I've seen before include "Emergency message" , "Call for help" , "Help initially, Mr Morse" , "Morse Code for help" , "Help code in 13 Across" .)