Innocent Methuselah framed by villain on tape (5)
I believe the answer is:
naive
'innocent' is the definition.
(similar in meaning)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for naive that I've seen before include "Simple-minded" , "Artless, innocent" , "Inexperienced, innocent" , "Too trusting and impractical" , "Ingenuous and gullible" .)