However, a late Lucas Digne goal meant that Villa got all the points, with Luton having previously rallied from 2-0 down to make it 2-2.
Speaking afterwards, Clark said: I feel sick, I really do.
Chasing games every week is not good, giving two goals away every week, a mountain to climb every week, but it shows the character we've got. I know we keep saying it every week so it's a bit boring at the minute, but you can't keep giving 2-0 head starts away.
We fight to the end and then obviously switch off at the last minute for the goal which is disappointing, because from 2-0 down a point's a good point in the end.
It's tough, we keep making the same mistakes every week, so it's something we need to address. It's nothing to do with tactics from us, it's just individual errors that are costing us.
We just need to stick together as a team and iron it out ourselves in the changing rooms and in the meetings and we need to improve quickly as we're running out of games. We said our home games are going to be vital this season so that's another one that's slipped away from us and we're on a bit of a losing streak in the league which we need to change."