Precipitate downfall of brash hangers-on in court (10)
I believe the answer is:
cloudburst
'precipitate downfall' is the definition.
'brash hangers-on in court' is the wordplay.
'brash' becomes 'loud' (I've seen this before).
'hangers-on' becomes 'burs' (a bur is a prickly, clingy plant part).
'in' is an insertion indicator.
'court' becomes 'ct'.
'loud'+'burs'='loudburs'
'loudburs' placed into 'ct' is 'CLOUDBURST'.
'of' acts as a link.
(Other definitions for cloudburst that I've seen before include "Sudden, heavy downpour" , "sudden shower" , "Sudden rainstorm" , "dramatic downfall" , "storm" .)