The term 'SAILOR's Quaff' is a slang term for an alcoholic beverage, usually rum, that is consumed by sailors. The crossword solution for this term is 'GROG', which is a mixture of rum, water, and sometimes other ingredients such as lime juice or spices. GROG was traditionally served to sailors on British naval ships in the 18th century, and the term has since become synonymous with any alcoholic drink consumed by sailors.