Drop the clutch - Take your foot off the clutch pedal quickly.
Slip the clutch - Not familiar with the term. Could be a northen hemisphere thing
Slipping clutch - This is what happens when the clutch is worn. Not good, get it fixed.
Ride the clutch - Partly taking your foot off the clutch such that the gearbox is engaged, but the clutch is not fully released. Technique used by some who have difficulty doing hill starts in a manual. Not good, will result in a slipping clutch eventually. Perhaps this is the equivalent term for 'slip the clutch' ?
I can remember the days when I had no idea what these terms meant, however the Internet was not invented then and I couldn't do a quick google search to find the answers