What
@Ron said above.
Except this.
Which isn't quite correct. The push rod fits into a hole in the side of the brass bush. THe hole is drilled deep into the bush side, put it doesn't go all of the way through. But - as Ron said - sometimes it can wear - in this case all the way through and out the other side.
Check it as he said. Its quick, its easy and cheap - if that it what has happened.
Normally wearing through isn't what happens. Often the person assembling the clutch lever doesn't manage to get the push rod inside the hole, and it sits on the outside of the bush.
When this happens, the lever is tight, and the clutch is nearly always partially disengaged. As the engine heats up, the fluid expands and it become fully disengaged, resulting in no drive.
But it doesn't sound like that is what has happened here. You'll know when you take the lever off.
Tip -Before you replace the bush, put a felt tip mark on the top of the bush, so line up with the location of the hole. You won't then have to guess where the hole is for the push rod.