[woodsman]

When clutches wear out there is a tendency for them to slip at low revs in the higher gears. This can go on for a long time (months). With a sudden onset of a loss of drive it indicates something else has occurred. With smoke bellowing out, a burnt smell and a loss of drive it points to a fluid or burnt disc that needs immediate attention. It could be a blown rear main seal which allows oil to soak the clutch lining.