Possible Clues:

• Entitlement to fish, one on either side of Tees?
• Conservative aspect of a good number of degrees?
• Square with the Tory viewpoint?
• How the correct way to fish makes it all square
• That makes it all square
• Proper perspective is something geometricians know about
• Ninety, to a degree? That's correct
• One of four in a rectangle
• Ninety-degree corner
• Feature opposite the hypotenuse, and a description of one of this puzzle's circled words