Crossword Genius

A mostly dreary time — but not for children (5)

Ross

I believe the answer is:

adult

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

'not for children' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for adult that I've seen before include "I wasn't born yesterday" , "not green" , "One no longer young" , "used to describe dirty movies" , "Full-grown" .)

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