No longer with us, former Tory leader in court (7)
I believe the answer is:
extinct
'no longer with us' is the definition.
(extinct means no longer existing)
'former tory leader in court' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'leader' suggests taking the first letters.
'court' becomes 'ct' (abbreviation used in road names).
The first letter of 'tory' is 't'.
'ex'+'t'+'in'+'ct'='EXTINCT'
(Other definitions for extinct that I've seen before include "Having died out, perished" , "gone for ever" , "Of volcano, no longer active" , "finished" , "No longer existing" .)