Leave without a thing (4)
I believe the answer is:
exit
'leave' is the definition.
(I know that leave can be written as exit)
'without a thing' is the wordplay.
'without' becomes 'ex' (Latin).
'a thing' becomes 'it'.
'ex'+'it'='EXIT'
(Other definitions for exit that I've seen before include "Withdrawal" , "walk away" , "Move out" , "farewell!" , "[DOOR] ?" .)