It's called a bridlepath. Or if you mean shaving the mane, it means to 'hogg' the mane.
If you are talking about shaving about a 1-inch section of mane behind the horse's ears, that's called a bridlepath. It is the area that the halter or bridle sits on.
a bridlepath :)
A Bridlepath
When you clip or shave the section of mane behind the horses ear, it is called the bridle path. It is on www.Howrse.com riding level 2.
It is called a buzz mane
Bridlepath
Bridlepath
Bridlepath
A Bridal Path.
A bridle path.
The bridle path
It is called a bridleway