Deal with one outburst (6)
I believe the answer is:
tirade
'outburst' is the definition.
(I've seen this before)
'deal with one' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'deal' could be 'trade' (synonyms) and 'trade' is located 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" , "A long abusive denunciation" , "Prolonged speech of abuse" , "Inclination; fish" , "A prolonged outburst of abuse" .)