Clearing the deficit is possible....but not along with tax cuts.
Clearing the debt is also possible, but not while still paying state pension benefit, or while funding a "free at point of treatment" health service.
And in any case, the U.K. has been in debt for a few hundred years, many times by a few hundred percent of GDP. Yet now a debt of 80% (+-) of GDP is a catastrophe?
Clearing the debt/deficit is a useful goal to persuade idiots to have less, pay more and (for all I know) die earlier.