Declamation (6)
I believe the answer is:
tirade
'declamation' is the definition.
(I know that tirade is a type of declamation)
This is all the clue.
(Other definitions for tirade that I've seen before include "Torrent of abuse" , "Flow of invective" , "A long abusive denunciation" , "Broadside of denunciation" , "Verbal outburst" .)