Tongue-lashing from one stuck in traffic (6)
I believe the answer is:
tirade
'tongue-lashing' is the definition.
(I've seen this in another clue)
'one stuck in traffic' is the wordplay.
'one' becomes 'i' (Roman numeral).
'stuck in' means one lot of letters goes inside another.
'traffic' becomes 'trade' (traffic can mean illegal trade).
'i' inserted inside 'trade' is 'TIRADE'.
'from' is the link.
(Other definitions for tirade that I've seen before include "Intemperate outburst" , "Flow of invective" , "Blast of criticism" , "Verbal outburst" , "A prolonged outburst of abuse" .)