Strongly affected, rascal left and behaved (5)
I believe the answer is:
acted
'behaved' is the definition.
('act' can be a synonym of 'behave')
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for acted that I've seen before include "produced an effect" , "Behaved in a certain manner" , "Took part in play" , "Worked" , "Play a role" .)