"To halve the deficit" means to reduce the deficit by half. The deficit refers to the amount by which the government's expenses exceed its income. So, halving the deficit means cutting it in half to make it smaller. Full definition
He added: «All it needs now is for Gordon to produce a new plan for halving the deficit in 12 weeks and we're finished.» (politics.co.uk)
Concerned to yank back economic credibility from the Tories, he reaffirmed the Darling plan to halve the deficit over the course of the parliament, and made points around the need to develop a proper industrial strategy. (leftfutures.org)
Diafra Sakho doubled their advantage just after the half hour mark and the visitors held on for all three points despite Kevin De Bruyne halving the deficit with a goal on his full debut for City and Pellegrini was disappointed to lose at home for the second time in four days: (caughtoffside.com)