Reviling a form of transport I have (7)
I believe the answer is:
abusive
'reviling' is the definition.
(thesaurus)
'a form of transport i have' is the wordplay.
'form of transport' becomes 'bus'.
'i have' becomes 'I've' (contraction of 'I have').
'a'+'bus'+'ive'='ABUSIVE'
(Other definitions for abusive that I've seen before include "Insulting, being harshly critical or offensive" , "scathing" , "Insulting, foul-mouthed" , "Rude, insulting" , "Given to hurling insults" .)