Most front (and rear) cable clamp bolts are M5x8 socket cap, about 10p from any fastener shop.
The bigger problem is that if the bolt has gone, the tabbed washer that sits under it has probably gone too. The bolt and washer kit is <£5, order from any shop which sells Shimano.
Have you been to Beeline? They used to be the proper cyclist's choice back in the day.
Most front (and rear) cable clamp bolts are M5x8 socket cap, about 10p from any fastener shop.
The bigger problem is that if the bolt has gone, the tabbed washer that sits under it has probably gone too. The bolt and washer kit is <£5, order from any shop which sells Shimano.
Have you been to Beeline? They used to be the proper cyclist's choice back in the day.