How do I color grade only part of a clip?

I am very new to Resolve, having used Avid for over 20 years.
When trying to color grade a shot in Resolve 17, the whole clip is affected.
I have a 90 minute clip of an orchestral concert. Some sections of the clip are darker that others. How can I color grade just the darker parts of my clip without effecting the whole 90 minutes?
Many thanks and kind regards, Jason.

You can make that section into a separate clip by placing the playhead at the start of the section and pressing Ctrl+\ to split it. Do the same at the end of the section. you now have a separate clip which you can grade by itself and add a cross dissolve front and end to blend it with the rest.
Here's a quick example.