Old custom that's forced return (11)
I believe the answer is:
extradition
'forced return' is the definition.
'extradition' can be an answer for 'return' (thesaurus). I am unsure of the 'forced' bit.
'old custom' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'custom' becomes 'tradition' (synonyms).
'ex'+'tradition'='EXTRADITION'
'that's' is the link.
Can you help me to learn more?
(Other definitions for extradition that I've seen before include "Sending back" , "The handing over of a criminal to another country" , "Return to original state" , "Handing over of a criminal between nations" , "delivery from abroad" .)