Vivacity or vitality (4)
I believe the answer is:
life
I believe this is a double definition.
'vivacity' is the first definition.
(I've seen this in another clue)
'vitality' is the second definition.
(I've seen this before)
(Other definitions for life that I've seen before include "Birth to death" , "Vitality, vigour" , "and 12 Down: Biology, medicine, etc" , ""But an empty dream" (Longfellow) - "As tedious as a twice-told tale" (Shakespeare)" , "Animation" .)