Old Egyptian city ready to interrupt work schedule (7)
I believe the answer is:
rosetta
'old egyptian city' is the definition.
(ancient city in Egypt)
'ready to interrupt work schedule' is the wordplay.
'ready to' becomes 'set' (synonyms).
'interrupt' indicates putting letters inside.
'work schedule' becomes 'rota' (I've seen this before).
'set' inserted within 'rota' is 'ROSETTA'.
(Other definitions for rosetta that I've seen before include "Town in Egypt where famous stone was found" , "Tablet that was the key to deciphering Egyptian hieroglyphs" , "town of old on the Nile" , "Inscribed basalt slab (found 1799), key to deciphering Egyptian hieroglyphs" , "The - Stone helped read Egyptian hieroglyphics" .)