what pest has burrowed into my clematis buds causing deformed flowers
Clematis flower buds attacked by a pest, which burrowed in and resulted in deformed flowers.
Certified GKH Gardening Expert
Most likely your damaged/deformed blooms are a result of cold damage. This article will help with that: https://www.gardeningknowhow.com/plant-problems/environmental/tips-for-saving-cold-damaged-plants.htm
If you still feel it is a pest, then thrips might be the culprit. Here is more information: https://www.gardeningknowhow.com/plant-problems/pests/insects/controlling-thrips.htm