Union in fun dismissing leader (8)
I believe the answer is:
alliance
'union' is the definition.
(I know that alliance is a type of coalition)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for alliance that I've seen before include "Formal agreement" , "Confederation" , "Group acting together for common cause" , "Wanting marriage" , "League - treaty" .)