Lethargic, unlike Ko-Ko? (8)

I believe the answer is:

listless

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'lethargic' is the definition.
(similar in meaning)

I cannot understand how the remainder of the clue works.

(Other definitions for listless that I've seen before include "Devoid of energy or interest" , "Without energy or vitality" , "Low-spirited" , "Lacking enthusiasm or energy" , "Devoid of spirit or energy" .)

I've seen this clue in The Independent.

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