Deal with one denunciation (6)
I believe the answer is:
tirade
'denunciation' is the definition.
(I know that tirade is a type of denunciation)
'deal with one' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
'deal' could be 'trade' (synonyms) and 'trade' is present in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tirade that I've seen before include "Loud harangue" , "Sustained abuse" , "A long, vehement harangue" , "Stream of invective" , "Furious denunciation" .)