Some members of the Pedants' Union might argue that 'two sailors on vacation' should indicate TS (or TWOSS), but I think it's a decent clue, even if the 'on vacation' device is starting to get a bit over-used (not least by me, I'm afraid!)
'On vacation' is a common (too common?) crossword device, meaning to empty, take out the contents of something... Two would be T o and Sailors becomes S S. TO SS, Toss.