Refuse to admit what's concealed by the downtrodden youths (4)
I believe the answer is:
Here is my best explanation:
'refuse to admit' is the definition.
'what's concealed by the downtrodden youths' is the subsidiary indication.
'what's concealed' says the answer is hidden in the clue.
'deny' is hidden in the letters of 'by downtrodden youths'.
(Other definitions for deny that I've seen before include "Do not admit", "Controvert", "Refuse to admit the truth", "Refuse to give", "Declare untrue", "Refuse to accept", "Declare non-existent", "Refuse to admit (something)", "Refuse to grant" and "Refute, contradict".)