"Peace!"
'peace' is the definition.
(Greeting from the Hebrew for 'peace')
This is all the clue.
(Other definitions for shalom that I've seen before include "Jewish word of greeting or leave-taking" , "Hebrew "ciao"" , "Jewish salutation, meaning "peace"" , "Israeli greeting" , "Hebrew greeting meaning peace" .)
(Other definitions for later that I've seen before include "at a future date" , "there's more behind" , "Alter (anag.)" , "When to see you?" , "Afterward, subsequent" .)