I have a 1966 Tamerlane it has a metal clip that runs parallel to the back of the bow and is mounted inside the window just ahead of the rest.I'm not sure what it is except it looks like something used to hold the arrow.
Anyone have any idea what it is. I've looked in the Bear Catalogues of the 6os and can't find one.

Sounds like a riser mounted clicker for target shooting.  Drawing the point just past the clip causes the clip to click back against the riser triggering the release.  Just a guess.

They were used with nib target points mainly.