How many letters does the top answer for “a genus of trees including the olive.” have?

The most common answer is olea (4 letters).

Crossword clue: a genus of trees including the olive.

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

olea 4 letters web-def

evergreen trees and shrubs having oily one-seeded fruits

a genus of trees including the elm. 60% similar → ulmus

a genus of palms including the date tree. 50% similar → phoenix