From Longman Dictionary of Contemporary Englisha hostage to fortunea hostage to fortuneRISKsomething that you have promised to do that may cause you problems in the future → hostage
Examples from the Corpus
a hostage to fortune• Senior Tories who dismissed the tax guarantee as a hostage to fortune will feel vindicated by Mr Hague's backdown.• But this development of local state institutions can be a hostage to fortune.• Making objectives explicit is a hostage to fortune and the failure to do so may reflect a shrewd awareness. 2. 