Cry “Thesis produces wild laughter” (9)
I believe the answer is:
hysterics
'wild laughter' is the definition.
(I've seen this before)
'cry thesis produces' is the wordplay.
'produces' indicates anagramming the letters.
'cry'+'thesis'='crythesis'
'crythesis' is an anagram of 'HYSTERICS'.
(Other definitions for hysterics that I've seen before include "Uncontrolled emotions or outbursts" , "Wild laughter" , "great glee" , "seizure" , "Uncontrollable laughter" .)