Possible Clues:

• Liable to change
• Not set in stone
• Crompton's making out the bill that's unsettled
• Varying dose of LSD swallowed by drug transporter
• Label inside slipper is not stuck down
• Subject to change; fickle
• Greek character leading the board? That may be changed
• Bill carried by beast of burden - that's subject to change
• Lame - but can be changed
• Inconstant