How many letters does the top answer for “capital of yemen” have?

The most common answer is aden (4 letters).

Crossword clue: capital of yemen

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

aden 4 letters wd-fact

an important port of Yemen; located on the Gulf of Aden; its strategic location has made it a major trading center of so

sanaa 5 letters wd-fact