The cleric already has a very impressive array of spells, a good number of which are equivalent or better than the arcane version anyway. I am unsure what staple spell would make this feat overpowered in their hands 
Especially with, as you said, the domains giving out so many anyway.
As I have seen lots of ideas with the psionic version floating around I have a bit of experience with how those sort of things go. Spending a feat for a single spell seems like a pretty high cost. Just making it worthwhile, from a power point of view since it can always be worthwhile in flavor, might be difficult.
I'd have no problem with a sorc picking up some random cure XXX spell, or a wizard running around with righteous might.
In most cases it would be sortof equivalent to spending a feat instead of paying some exp now and then to cast it anyway (not the greatest of examples, but it helps show the point).

Especially with, as you said, the domains giving out so many anyway.
As I have seen lots of ideas with the psionic version floating around I have a bit of experience with how those sort of things go. Spending a feat for a single spell seems like a pretty high cost. Just making it worthwhile, from a power point of view since it can always be worthwhile in flavor, might be difficult.
I'd have no problem with a sorc picking up some random cure XXX spell, or a wizard running around with righteous might.
In most cases it would be sortof equivalent to spending a feat instead of paying some exp now and then to cast it anyway (not the greatest of examples, but it helps show the point).