Posted: 10/06/2017 at 15:13
The attractive seedheads are one of the plus points of Markham's Pink ... leave them on. It's a lovely clematis and yours is still young. http://www.taylorsclematis.co.uk/clematis-markhams_pink.html
No need to prune this clematis, just let it do it's thing, but next year in early March give it a feed with specialist clematis food (available from garden centres) and a good watering. That'll encourage it to produce more flowers next April/May.