Treacherous rogues and rebels (9)
I believe the answer is:
dangerous
'treacherous' is the definition.
(similar in meaning)
'rogues and rebels' is the wordplay.
'rebels' indicates anagramming the letters.
'rogues'+'and'='roguesand'
'roguesand' anagrammed gives 'DANGEROUS'.
(Other definitions for dangerous that I've seen before include "Perilous, unsafe" , "Pope: 'A little learning is a . . . . . . . . . thing'" , "Hazardous" , "posing risk" , "Harmful, injurious" .)