Is it permissible to pay Zakat in kind (food or clothing) instead of cash, for fear that the poor person might spend it on something unbeneficial or sinful?

The fundamental principle is that zakat should be taken from wealth and given to the poor. It is permissible to disburse zakat to needy relatives who are not dependents of the zakat-giver, by giving them the money directly and allowing them to authorize someone to purchase what they desire. It is not permissible to buy books or goods with zakat funds and then distribute them; rather, zakat must be paid in cash to its rightful recipients, based on the Almighty's saying: "Indeed, zakat expenditures are only for the poor and for the needy and for those employed to collect [zakat] and for bringing hearts together [for Islam]..." If the recipient of zakat is disobedient and there is a concern that they might spend the money in disobedience, then zakat can be given to someone who will spend on their behalf, or they can be asked to authorize the zakat-giver to purchase their necessities. This means the zakat-giver would ask the head of the household about their essential needs and then buy them, which is permissible, and the zakat would then be in its proper place.