Sound of jeers in court session (5-2)
I believe the answer is:
booze-up
'session' is the definition.
(I've seen this before)
'sound of jeers in court' is the wordplay.
'sound of' indicates a 'sounds like' (homophone) clue.
'jeers' becomes 'boos' (boos from a crowd).
'in court' becomes 'up' (up before a judge).
'boos' sounds like 'booze'.
'booze'+'up'='BOOZE-UP'
(Other definitions for booze-up that I've seen before include "Bout of serious drinking" , "Heavy drinking session" , "Drinking spree" .)