Clunking sound front right

My daughter drives a Ford Escort ZX2. Occasionally when she is stopped at a light and has her foot on the brake she hears a load clunking which she thinks is coming from the front right. It's only when her foot is on the brake. If she is sitting and removes her foot from the brake it stops. It does not happen when she is braking either. Only when she is stopped with her foot on the brake. We had someone look at the brakes and they said they were fine. The motor mount however was cracked and we had that replaced along with a tune-up. We thought that was the noice but it just happened again. Any help would be much appreciated