Sending might work. The target knows the source of the Sending spell, so you will need to be clever about how it is implemented so he doesn't just immediately rid himself of the item. If the item is cursed, he might have some problems getting rid of it, assuming he could be tricked into attuning to it in the first place. As a cleric, he would have easy ways to get rid of a curse though. You might have to brainstorm something specific to your circumstances that would prevent him from just destroying the source of the spell.