Energetic agent frames right and left (9)
I believe the answer is:
sprightly
'energetic' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for sprightly that I've seen before include "Lively" , "Moving nimbly" , "Brisk" , "Active" , "Vivacious" .)