I'd also be inclined to change out that tire completely or at the very least to move it to the rear. I'm curious--have you taken it off the rim and looked at it from the underside? When I ride on clinchers I ride on Michelin PRO4s and when they're scrapped I use them as for various reasons. I've take safety blades to those things and they are really tough to cut through! Some tires are more durable than you might imagine; but when there is doubt it is best to err on the side of caution.