Hedge Problem

Hi,  I am a novice at this, but was wondering if anyone could help with my hedge.  I have recently noticed patches are dying / going bare, as per the photos attached. I can see a patch at the back, and a similar one at the front (directly in front).  I had a few queries:

1. Is there anything I can do to stop the patch getting worse / spreading?

2. Should I cut these patches out - the plant seems very dry and dead in these bits.

3. Should i leave it totally (ie. its a normal thing and will grow back in the spring)

Many thanks for any advice

!