Commando clutch cable end too small for clutch lever

Is it a tolerance issue or a different style of pivot? If it's a tolerance issue send it back. If you have the alternative type with a peg and pea system again tell the supplier, he should send you the correct type for your vehicle. 

It looks as though it could be the type of cable that should have the sleeve that surrounds the "small" nipple, It's fitted in an attempt at reducing friction around the nipple with less strain upon the cable and preventing it snapping.
 Call your supplier to confirm.

The nylon lined nipples are smaller than the hole in the lever, but they last far longer than the solid nipple which fits nicely as those cables don't last. We have in the past asked our supplier (Venhill) to source a better nipple with a nylon liner and they said they could not do it. 

I've got the same query. The old cable nipple measured 9mm dia x 14mm long and filled the hole in the lever perfectly. The new cable nipple measures 8mm dia x 9mm long and just doesn't look right in the lever. Can anyone who's fitted the newer cable please confirm that it's fine?

It's the spare I carry - hopefully not to come out of its bag for a while

Your picture shows the lever has been strained/distorted were the nipple sits widening the cable slit causing the new cable fitting to look too small, either squeeze the lever to close up the gap or fit a new lever.

... that nipple with the plastic surround would be suitable for a pressed steel lever as illustrated. They're meant for cast alloy levers where there's much more contact between the lever and the nipple.

I wasn't happy with the short nipple/nylon sleeve cable with how it sat in the lever, it was held on the piss, putting the nipple/cable under too much stress. This effect is worse with worn lever pivots etc. Made a new longer steel nipple along with a graphite filled nylon sleeve. Fills the hole perfectly, sits straight and doesn't stress the cable.
I,m not surprised Venhill won't supply these cable ends, No repeat business...