A late penalty from Clifton's Gareth Knox ended Launceston's three-match National Two South winning streak as they went down 24-21 in Bristol.
The Cornish All Blacks had clawed their way back into the match after going in 18-8 down at the break.
Ben Hilton's try just before half-time replied to tries from William Pomphrey and Thomas Pool and two Knox penalties.
Lewis Webb's try, allied to Kieron Lewitt's three penalties, helped level at 21-21, before Knox's winning kick.
Levitt also improved Webb's second-half try for an 11-point haul, but missed with his first conversion attempt.
Victory sees Clifton leapfrog into seventh in the National Two South, Launceston dropping to eighth ahead of this Saturday's Cornish derby with Redruth at Polson Bridge (17 December, 1430 BST).