There is no easy way that I know of. It would be helpful if you posted a larger size photo. For details on how to do that click:
HERE .
The first step that I did was to look at the channels in RGB, CYMK, and Lab.
I decided to do what has been suggested, and that is to use the channel mixer and select the red channel and convert to black and white. Then work on the spot in Grayscale using a new layer with overlay blending mode and a black or white brush.
Next colorize the grayscale.