Fighting lethargy? (8)
I believe the answer is:
inaction
'lethargy' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for inaction that I've seen before include "Failure to exert oneself" , "lack of engagement" , "Sluggishness" , "Lack of anything being done" , "Immobility" .)