hi there ty for reply the bolt in question is the one you tighten to clamp the left shifter whichis the middle mech to the hande bar to stop it movin around have done best shot i can think of to show what i mean.
Drill it out. Buy an M7 tap tap out, but an M7 bolt and cut it to the right length and srew it in. I'd say drop into my shop but you are proabably a long way away.