Not sure but that could be normal clutch clunking, unless this is something new that just started , most will clunk from clutch engagment and as normal clutch wear takes place it will clunk a bit. If the shifter is setting it the slot and no gear grinding is taking place 10 to 1 it's the clutch. could even be from an old belt , I have almost 4K on my 2011 and the clutch will clunk at engagment for sure , still running factory belt as well.
Hope this helps
Agree with the normal engagement sound. With engine idling and shifted from neutral into forward gear, when you first barely start to move, an awful sounding clunk MAY happen. It's the helix setting into the secondary inner sheave fully. Try to ease forward until you hear it, then is good to go full on. Its also normal if you don't hear it every time as at times it will seat fully when gear is first engaged.
The newest models have a revised helix that has pretty much eliminated that clunk with a torsional spring preload design.