Refuse to admit what's concealed by the downtrodden youths (4)
I believe the answer is:
deny
'refuse to admit' is the definition.
(thesaurus)
'concealed by the downtrodden youths' is the wordplay.
'concealed' indicates a hidden word.
'DENY' is hidden within 'by downtrodden youths'.
'what's' is the link.
(Other definitions for deny that I've seen before include "Declare non-existent" , "Gainsay" , "Contradict, refuse" , "Abnegate" , "Forbid; contradict" .)