Welcome to the site.
Regarding your question .... IMHO the upper part that got the shot is not the tip of the horizontal stabilizer elevation control surface because these parts ( not only of the Ju-88 ) were made of either the pressed plate, thin relatively or a wood but not of the solid piece of metal. Judging but its shape it is a pices of a propeller blade tip. The another piece of the blade seems to be used for the base. The clock attached to it, is the WWII Luftwaffe Junghans J30 BZ ( also Swiss made Juvenia J30 BZ ) made by the Gebr. Junghans, Schramberg and a couple of other manufacturers, cockpit clock with chronograph function. It was used in many of different Luftwaffe kites eg. Bf 109, Fw 190. These clocks are also known as the Borduhr Bo-UK*. The Fl numbers could be Fl.23885, Fl.23886, Fl.23888 depending on the time of producing.