Amalgamation (6)
I believe the answer is:
merger
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">amalgamation</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that amalgamation can be written as merger)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for merger that I've seen before include "The joining of two business enterprises" , "Joining of businesses" , "Convergence" , "The combining of two businesses" , "Act of combining" .)