Leave cave at order (6)
I believe the answer is:
vacate
'leave' is the definition.
(vacating is a kind of leaving)
'cave at order' is the wordplay.
'order' indicates anagramming the letters.
'cave'+'at'='caveat'
'caveat' anagrammed gives 'VACATE'.
(Other definitions for vacate that I've seen before include "Make empty" , "Move out and leave empty" , "Clear out and leave empty" , "Withdraw as from premises" , "Leave (a position)" .)