Suggesting a lack of maturity (7)
I believe the answer is:
puerile
(Other definitions for puerile that I've seen before include "Babyish" , "Childish, immature" , "Childish, silly, trivial" , "Childishly silly" , "Infantile" .)
I believe the answer is:
puerile
(Other definitions for puerile that I've seen before include "Babyish" , "Childish, immature" , "Childish, silly, trivial" , "Childishly silly" , "Infantile" .)