I'm still out of town (coffeeneuring at Tosi's in St Joe, MI this morning). I will disassemble things when I'm back home (on the weekend) and take pix. My guess is this was how Miyata did their seatpost binders, so it was probably a stick part of some framebuilding supply place inn the early 80s. My understanding is the Univega Super Speciale frame was in reality a Miyata something-or-other. This thought is reinforced by the comment by
SurferRosa about using JB Weld to solve the same issue on a Miyata 812.