Deportation, one-time practice (11)
I believe the answer is:
extradition
'deportation' is the definition.
(thesaurus)
'one-time practice' is the wordplay.
'one-time' becomes 'ex'.
'practice' becomes 'tradition' (tradition is a kind of practice).
'ex'+'tradition'='EXTRADITION'
(Other definitions for extradition that I've seen before include "Process of handing person over to foreign justice" , "Handing over offender" , "Process of handing over a criminal to a foreign jurisdiction" , "Handing over of someone to a foreign government" , "delivery from abroad" .)