Cistus, rock rose, half the plant appears to be dead?

Grays

Hi there,
My Cistus appears to be very unhealthy, about two thirds of the plant appears to be dead/dieing, the rest seems healthy and fine.
What do you think I should do? Should I completely cut out the majority of the plant that appears unhealthy?
Hope the photos can show the problem.
(The second photo is the healthy part)
Thanks.

Posy

I find them quite tender. A late frost or cold wind knocks them right back. I would wait a bit to see what recovers, then cut out dead bits. They sometimes recover and bounce back but not always.