Liveliness of a cartoon (9)
I believe the answer is:
animation
This clue is a double definition.
'liveliness' is the first definition.
(synonyms)
'a cartoon' is the second definition.
(I know that cartoon can be written as animation)
'of' acts as a link.
(Other definitions for animation that I've seen before include "Vigour; film technique" , "Making of cartoons" , "Liveliness and vigour" , "Art of cartoon making" , "Liveliness and enthusiasm" .)