A loner despised, abandoned, no longer regarded as an individual (14)
I believe the answer is:
depersonalised
'no longer regarded as an individual' is the definition.
'a loner despised abandoned' is the wordplay.
'abandoned' indicates an anagram.
'a'+'loner'+'despised'='alonerdespised'
'alonerdespised' is an anagram of 'DEPERSONALISED'.
(Other definitions for depersonalised that I've seen before include "Being stripped of individual recognition" , "without character" .)