Bothersome kid mostly detained by brave individual (7)

I believe the answer is:

hellion

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

'bothersome kid' is the definition.
(informal term for a misbehaving child)

'mostly detained by brave individual' is the wordplay.
'mostly' means to remove the last letter.
'detained' becomes 'held' (I've seen this before).
'by' is a charade indicator (letters next to each other).
'brave individual' becomes 'lion' (lion is a kind of individual. I am not sure about the 'brave' bit.).
'held' with its final letter taken away is 'hel'.
'hel'+'lion'='HELLION'

Can you help me to learn more?

(Other definitions for hellion that I've seen before include "Rowdy or mischievous person" , "Person fond of devilry, trouble-maker" .)

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.