Core mechanics are the bee's knees. All the cool games have one. For my purposes, I'm defining a core mechanic as the single process that is used to resolve the effectiveness of a character's action, regardless of what the action is. For example:
GURPS: Roll 3d6 + modifiers. If you get roll over your (stat + skill) then you fail, otherwise you succeed.
Dungeons & Dragons (3rd Edition): Roll 1d20 + stat bonus + skill bonus + situational modifiers. If you under some target number, you fail, otherwise you succeed.
I call Clout's core mechanic the "7/10 rule." Roll 1d12. If the roll is 7 or higher your result is a "partial success"; if the roll is 10 or higher your result is a "success." Anything else is a failure. You can then apply tags (though you'll probably need to spend clout to do so) to improve your results.