"Name a card. Reveal cards from the top of your deck until you reveal the named card. Set that card aside and discard the rest. You may play that card this turn. If you do, trash it. Otherwise, discard it during this turn's Clean-up."
To get this to a bit less text: Why would you want to name a card and not play and trash it? Of course, you could say name "Province" and lower the chance that it will come up in the next hand, but as we have all discussed this has only a minor effect, so I don't think it is worth a "You may", "If you do" and "Otherwise, ..." on the card.
And with this wording, you can't trash Estates with it, because you can't play them. If you are forced to play it, and without the "if you do", you could.
I think target trashing of Estates, and trashing of Coppers for terminal +$1 is not the worst card, +the cycling it has, is not the worst card. I wouldn't costs this at $4, because you don't want to spam this anyway. So the question is $5 or $3?.
In it's current form, ignoring combos with DarkAge, I don't see much use. Terminal trashing of Copper (at least this is not from hand) with a $1 bonus seems about the range of Moneylender, but I think it's weaker. It will work longer then ML, as it finds all the Coppers, but it gives $1 less when played, which is a big deal I think. When you trash Coppers, you need to build another source of money, otherwise these Estates you can't trash will kill you. Moneylender has a good chance of bring you to Gold, or at least a power $5, while with $1 less this doesn't look so great, and will often result in Silver.
Trashing of something else will very rarely occure. You can't trash Curses, you don't get a real benefit from trashin other than playing the card one last time (but if that would be important, why do you want to trash it?).
