Sickly Lord Byron's only character that descends (6)
I believe the answer is:
sugary
'sickly' is the definition.
Both the answer and definition are adjectives. Perhaps there's an association between them I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for sugary that I've seen before include "Excessively sentimental" , "Excessively sweet or saccharine" , "Sweet, syrupy" , "Sweet, perhaps too much so" , "Over-sentimental" .)