Cry out loud (4)
I believe the answer is:
wail
'cry out loud' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for wail that I've seen before include "Cry of lament" , "Lament loudly" , "Long cry, sounds like cetacean" , "Long cry, as of siren" , "(Make a) plaintive cry" .)