Crossword clue: the hindmost mast of a three-masted vessel, or of a yawl-rigged vessel.
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
third mast from the bow in a vessel having three or more masts; the after and shorter mast of a yawl, ketch, or dandy