Is there a way to avoid the suspicion of usury when repaying a loan of 10,0 pounds with an increase of 2,0 pounds, knowing the dire need for the money, such as paying part of it as charity (sadaqah) or zakat?

This transaction is impermissible because it constitutes explicit usury (riba). Any increase in a loan, or any benefit accrued by the lender, is usury. The way out of this is for the commodity to be bought for a certain price, and then the buyer—who is in need of cash—sells it for a higher price. This is known as the issue of Tawarruq.