From Longman Dictionary of Contemporary Englisha powder kega powder kegSERIOUS SITUATIONa dangerous situation or place where violence or trouble could suddenly start Since the riot, the city has been a powder keg waiting to explode. → powder
Examples from the Corpus
a powder keg• Ireland - home, as Joseph called it - had been a powder keg since the Easter Rising three years ago.• The place was a powder keg. 