From Longman Dictionary of Contemporary Englishhold the forthold the fortRESPONSIBLEto be responsible for something while the person usually responsible for it is not there She’s holding the fort while the manager’s on holiday. → hold
Examples from the Corpus
hold the fort• Junior Bryant has to hold the fort.• Filling the breach, holding the fort, and that kind of thing.• The evening was to take place as planned and Faith would hold the fort at Oaklands.• The three of you will be holding the fort in the kitchen tonight.• Just the three of you going to be holding the fort tonight.• You got us into this, was my uncharitable thought, now you hold the fort while we climb out of it.• It was Major Herriott's turn to get out of the office, having held the fort whilst his leader had been away. 