Welcome to the site.
Are you sure the noise is coming from the clutch side? If not it could be in the chaincase. With the back of the sled raised so you can spin the track, have a trustworthy helper press the throttle until the clutch engages and try to pinpoint the noise, maybe with the hood open so you can see and hear things go on. Use caution in doing this please.
Have the clutches ever been serviced? How many miles on the sled?