Angry words of one caught in traffic (6)
I believe the answer is:
tirade
'angry words' is the definition.
(I've seen this before)
'one caught in traffic' is the wordplay.
'one' becomes 'I' (Roman numeral).
'caught in' means one lot of letters goes inside another.
'traffic' becomes 'trade' (I've seen this before).
'i' put inside 'trade' is 'TIRADE'.
'of' is the link.
(Other definitions for tirade that I've seen before include "Verbal onslaught" , "A prolonged outburst of angry words" , "lecture" , "Loud harangue" , "Broadside of denunciation" .)