How many letters does the top answer for “a mediator who brings one thing into harmonious agreement with another” have?

The most common answer is harmoniser (10 letters).

Crossword clue: a mediator who brings one thing into harmonious agreement with another

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

harmoniser 10 letters wn-def

a mediator who brings one thing into harmonious agreement with another

harmonizer 10 letters wn-def

a mediator who brings one thing into harmonious agreement with another