Is it safe to have mantel clocks up on the mantel while having a wood burning fire?

It is safe to have a mantel clock on the mantel while having a wood fire going simultaneously. However, the same types of precautions should be followed as for all fires being in a controlled indoor environment. Do not allow flames to grow to such heights that they are uncontrollable as surrounding fixtures and furniture may catch on fire. Many fireplaces hold and insulate a fire fairly well and a mantel clock should be relatively safe to place on top of your mantel.