On vacation (4)
'on vacation' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for away that I've seen before include "Like some fixtures" , "At a distance, from home say" , "Having started" , "'Apart, remote (4)'" , "and 9: Christmas carol" .)
'on vacation' is the definition.
(off can mean away on holiday)
This is all the clue.
(Other definitions for off that I've seen before include "Temporarily not on the menu" , "Discontinued" , "On holiday" , "Away, at a distance" , "Rotten" .)
(Another definition for away from it all that I've seen is " In seclusion".)