Sally Ward once had The Court in tears of laughter (6)
I believe the answer is:
jester
'had the court in tears of laughter' is the definition.
I can't judge whether this definition defines the answer.
'sally ward' is the wordplay.
'sally' becomes 'jest' (I've seen this before).
'ward' becomes 'er' (I am not sure about this - if you are sure you should believe this answer much more).
'jest'+'er'='JESTER'
'once' acts as a link.
Can you help me to learn more?
(Other definitions for jester that I've seen before include "Court clown" , "Court fool" , "one entertaining in court" , "Court joker" , "Buffoon" .)