Possible Clues:

• Temporary alliance
• Such alliance may perhaps lead to fossilisation of a sort
• It takes one against fuel to lead a political alliance
• Alliance
• Alliance to adopt fossil fuel, perhaps
• Diplomats' success
• The alliance of carbonisation, perhaps
• It takes more than one for such carbonification, perhaps
• Might it be carbonification, perhaps, that needs such a merger? (9)
• Consortium supplying fuel - large quantity I received