[jayco]

Some times, if the clinker is not too large, you can turn the clinker breaker, if your forge is so equipped, and get the clinker to fall out the bottom.

Larger clinkers are more difficult of course.
You might insert a small poker with a hook on the end ,grab the clinker and pull it out sideways without disturbing the fire much.

You can also use a 'slice'........think flat shovel or spatula,,,,,,use it to lift up the fire with one hand, while you use the poker to hook the clinker.
It's easier than it sounds......