Juvenile, empty, junior, naive, ultimately? (6)
I believe the answer is:
jejune
'juvenile' is the definition.
(synonyms)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for jejune that I've seen before include "Barren, dull, unnourishing" , "Puerile" , "Naive, simplistic" , "Scanty or unsatisfying to the mind" , "Naive, immature" .)