Peculiarity of a train bore rambling (10)
I believe the answer is:
aberration
'peculiarity' is the definition.
(thesaurus)
'a train bore rambling' is the wordplay.
'rambling' indicates anagramming the letters.
'train'+'bore'='trainbore'
'trainbore' with letters rearranged gives 'berration'.
'a'+'berration'='ABERRATION'
'of' is the link.
(Other definitions for aberration that I've seen before include "Straying" , "Mental lapse" , "departure from normal" , "moral lapse" , "Slip" .)