That is where the trunk light's wire exits the trunk lid. The trunk light mounts in a similar hole close to the top edge of the lid (when open).
Do you have a pic of a trunk light mounted in that space on the lid? That would be of great help! Edt: Nevermind i just saw the reply rthomas with the pic.
But the cable is very visible there and what's the round hole for? Looks like a screw might've gone there?
So the wire goes attached to that plastic clip? And then inside the lid till it reaches the light socket?
Actually the wire retainer in that pic above is a 80's style clip with the Christmas tree style barb not the correct clip used on a Maverick. Here is a pic of the original broken nylon wire retainer...the other pic is showing the wire attached to the clip. The above photo does not have holes for the wire to loop through and requires electrical tape to secure the wire to the clip.