Wiktionary
bell the cat
vb. (context idiomatic English) To undertake a dangerous action in the service of a group.
WordNet
bell the cat
v. take a risk; perform a daring act; "Who is going to bell the cat?"
Usage examples of "bell the cat".
If the mice won't bell the cat, I guess the cat will have to do it himself.
Aesop stated it sardonically in the fable of the convention of the mice, when he inquired gently, 'Who is to bell the cat?