I found that a 2" wide spring clip (from stationary stores) fits nice and tight over a handlebar. A small flashlight could be secured with sturdy rubber bands to the wire arms.

That's creative. I'm wondering if there might be a better way to attach the light to the clip.

Must it be another office supply item?

I was thinking of that too, e.g., rivet a PVC pipe fitting to the clip and then put the flashlight in the pipe fitting - need to secure the flashlight there - but, the rubber band holds it so secure and the pipe fitting would interfere with the wire handles.

Maybe it doesn't need a better way to hold the flashlight to the clip. I will try it out and report back.