Just a guess that if the damsels get too close to the clowns they may not breed. The have to feel they have privacy (just like you would should you even attempt to breed)
She may be cleaning an area to lay the eggs.
In order to really make sure the babies survive you will need to put something in there that they can lay the eggs on and you can remove the item easily to save the eggs. Some recommend taking a ceramic 4"x4" tile and put it at an angle near where the clowns are hanging out, make sure to put the tile rough side up.