Money held in old court gone forever (7)
I believe the answer is:
extinct
'gone forever' is the definition.
(I've seen this before)
'money held in old court' is the wordplay.
'money' becomes 'tin' (old-fashioned slang term for money).
'held in' indicates putting letters inside.
'old' becomes 'ex' (prefix meaning former or onetime).
'court' becomes 'ct' (abbreviation used in road names).
'ex'+'ct'='exct'
'tin' put inside 'exct' is 'EXTINCT'.
(Other definitions for extinct that I've seen before include "Ended" , "Put out" , "never to be seen again" , "(Species) lost" , "Dead - obsolete - extinguished" .)