Tease cracking obsessive up leads to actual laughter in court (8)
I believe the answer is:
tribunal
'court' is the definition.
(synonyms)
'tease cracking obsessive up leads to actual laughter' is the wordplay.
'tease' becomes 'rib' (I've seen this before).
'cracking' indicates putting letters inside (inserted letters go into a gap or crack).
'obsessive' becomes 'nut' (informal term for a fan or aficionado).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'leads to' says to take the initial letters.
The initial letters of 'actual laughter' is 'al'.
'nut' backwards is 'tun'.
'rib' placed into 'tun' is 'tribun'.
'tribun'+'al'='TRIBUNAL'
'in' is the link.
(Other definitions for tribunal that I've seen before include "Board of officers appointed to investigate and report on matters of public interest" , "Court appointed to look into a particular matter" , "Hearing" , "A panel of judges" , "Assembly to conduct judicial business" .)