A4o is a weak hand out of position that early in tournament play. You should lay down on the flop after UTG raises. He has position on you the whole way, and is asserting that position early. You have only one pair with a weak kicker. Most likely he is either holding AJ or higher, or he hit two pair on the flop. Heck, he could have trips. Since you have no flush draw, you're dead to anything that he would likely have.