Spooner's escaped torment? That signals danger! (3,4)
I believe the answer is:
red flag
'danger' is the definition.
Both the answer and definition are singular nouns.
I also know that 'danger' relates to this answer.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for red flag that I've seen before include "Warning sign" , "Socialist banner?" , "Socialist symbol" , "A flyer" , "The ... ..., anthem of the British Labour Party" .)