Is zakat obligatory on money loaned to a brother, and on sums owed by others, and on money in the bank that has been held for a whole year, and how is zakat to be paid from the latter, and can zakat be disbursed to the needy for necessities such as clothing, knowing that they have their daily sustenance?

The money loaned to others is subject to Zakat (definition) from you, once it enters your possession and a full year has passed over it, regardless of whether the debtor is in financial difficulty or affluent. As for the money in the bank, Zakat becomes due on it from you once a full lunar year has passed since it entered your possession. It is not necessary to withdraw the money from the bank to pay Zakat. As for the recipients of Zakat, they include those in need of basic necessities such as clothing. Whoever is unable to obtain these is considered poor and eligible to receive Zakat.