From Longman Dictionary of Contemporary Englishnail in somebody’s/something’s coffinnail in somebody’s/something’s coffinDESTROYone of several bad things which help to destroy someone’s success or hopes Observers fear that this strike will be another nail in the coffin of the industry. the final nail in his coffin → nail
Examples from the Corpus
nail in somebody’s/something’s coffin• Another loss would be another nail in Branfoots managerial coffin.• Industry observers fear that this would be another nail in the coffin of the independent record industry.• It is another nail in the coffin of deterrence even if the first generation of cruise will be slow for such a role.• Was not the film's very name, Last Resort, another nail in Margate's coffin?• A final nail in the coffin had been hammered in by Wrede.• For me this was the final nail in the coffin of a terminally dull product.• It also is one more nail in the coffin of formal decor.• In the end, it was also the issue which secured a vital nail in the coffin of Britain's nuclear dream. 