Have groups of urban youths set on son? (7)
I believe the answer is:
possess
'have' is the definition.
(synonyms)
'groups of urban youths set on son?' is the wordplay.
'groups of urban youths set' becomes 'posse' (I am not sure about this - if you are sure you should believe this answer much more).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'son?' becomes 'ss' (I've seen this in other clues).
'posse'+'ss'='POSSESS'
Can you help me to learn more?
(Other definitions for possess that I've seen before include "Own, keep" , "Have as one's own" , "influence" , "Have ownership of" , "Consume" .)