Females sailed off (6)
I believe the answer is:
ladies
'females' is the definition.
(I know this)
'sailed off' is the wordplay.
'off' indicates an anagram.
'sailed' anagrammed gives 'LADIES'.
(Other definitions for ladies that I've seen before include "Lords' wives" , "Ideals for gentlewomen" , "Women of rank in the British peerage" , "Ideals for genteel women" , "Wives of knights" .)