Kittenish, playful (6)
I believe the answer is:
frisky
I believe this clue is a double definition.
'kittenish' is the first definition.
(I know that kittenish can be written as frisky)
'playful' is the second definition.
(similar in meaning)
(Other definitions for frisky that I've seen before include "Playful, full of energy" , "Animated" , "High-spirited" , "Lively like playful dog" , "In high spirits" .)