Rant coming from one stuck in traffic (6)
I believe the answer is:
tirade
'rant' is the definition.
(thesaurus)
'one stuck in traffic' is the wordplay.
'one' becomes 'i' (Roman numeral).
'stuck in' indicates putting letters inside.
'traffic' becomes 'trade' (I've seen this before).
'i' put within 'trade' is 'TIRADE'.
'coming from' is the link.
(Other definitions for tirade that I've seen before include "Prolonged abusive speech" , "Prolonged speech of abuse" , "Flow of invective" , "Furious denunciation" , "A long, vehement harangue" .)