Is it permissible for a Zakat institution to compel recipients of Zakat funds, specifically those categorized as "fi sabilillah" (in the way of Allah), to return the value of what they received to the institution if they violate conditions stipulated by that institution?

If Zakat (definition) funds are disbursed to an eligible recipient, they cannot be reclaimed from him, because they have become his property. However, if it becomes clear that he is not among those eligible, then it is obligatory to reclaim the funds from him to be given to those who are eligible.