Union, association (8)
I believe the answer is:
alliance
I believe this is a double definition.
'union' is the first definition.
(I know that alliance is a type of coalition)
'association' is the second definition.
(I've seen this before)
(Other definitions for alliance that I've seen before include "Kind of partnership with canaille" , "Formal agreement" , "Wanting marriage" , "Bond" , "Marriage - union" .)