Long rant (6)
I believe the answer is:
tirade
'long rant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tirade that I've seen before include "A long abusive harangue" , "Broadside of denunciation" , "A long, abusive outburst" , "Stream of invective" , "Long speech of angry criticism" .)