The command XCLIP is known as "Xref clip", but many might not know that XCLIP can be used to clip block what objects are displayed. To clip a block, start the XCLIP command by entering it at the command line or selecting Xref from the Modify menu > Clip. Select the block and follow the prompts to create a new boundary that should be used to clip the block.
This is how the SUPERHATCH command that is part of Express Tools works. It determines how the objects in a block can be placed within a given boundary and then clips the objects that don't fit nicely in that boundary. SUPERHATCH is a great command for creating custom hatch patterns based on images, blocks, wipeout objects, and xrefs. SUPERHATCH can be found under the Express menu > Draw > Super Hatch.