Not the right grown-up (5)

I believe the answer is:

wrong

I'm a little stuck... Click here to teach me more about this clue!

'not the right' is the definition.
I can't judge whether this definition defines the answer.

'grown-up' is the wordplay.
'up' indicates an anagram (letters get chucked up).
'grown' is an anagram of 'WRONG'.

Can you help me to learn more?

(Other definitions for wrong that I've seen before include "Not correct" , "Failing to come right" , "Unjust - incorrect" , "Inappropriate" , "Erroneous" .)

I've seen this clue in The Irish Independent.

Want a hint initially instead of a full solution? Install my app