Wildly funny (10)
I believe the answer is:
hysterical
'wildly funny' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for hysterical that I've seen before include "Violently emotional" , "Wildly uncontrolled" , "Emotionally unstable" , "Uncontrollably laughing or crying" , "extraordinary" .)