Organised ride Celt ruined (8)
I believe the answer is:
derelict
'ruined' is the definition.
(I've seen this before)
'organised ride celt' is the wordplay.
'organised' indicates an anagram.
'ride'+'celt'='ridecelt'
'ridecelt' is an anagram of 'DERELICT'.
(Other definitions for derelict that I've seen before include "Unsafe through neglect" , "Destitute; neglected" , "Left to fall into ruin like abandoned house" , "Of building, run-down and abandoned" , "Disused, neglected" .)