Diatribe from one stuck in traffic (6)
I believe the answer is:
tirade
'diatribe' is the definition.
(thesaurus)
'one stuck in traffic' is the wordplay.
'one' becomes 'i' (Roman numeral).
'stuck in' is an insertion indicator.
'traffic' becomes 'trade' (I've seen this before).
'i' placed into 'trade' is 'TIRADE'.
'from' is the link.
(Other definitions for tirade that I've seen before include "Fulmination" , "Furious denunciation" , "A prolonged outburst of abuse" , "Intemperate outburst" , "Loud harangue" .)