Group of youngsters pester antisocial character
I believe the answer is:
litterbug
'antisocial character' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'group of youngsters pester' is the wordplay.
'group of youngsters' becomes 'litter' (I can't explain this - if you can you should give a lot more credence to this answer).
'pester' becomes 'bug' ('bug' can be a synonym of 'pester').
'litter'+'bug'='LITTERBUG'
Can you help me to learn more?
(Other definitions for litterbug that I've seen before include "Trash dropper" , "Bad citizen" , "one leaving droppings" , "Rubbish dropper" , "filthy devil" .)