Fever, so ends in beauty sleep, blanketed (6)
I believe the answer is:
typhus
'fever' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for typhus that I've seen before include "Acute, infectious fever" , "Disease found in spy hut, strangely" , "Infectious disease with fever and purple rash" , "Infectious disease transmitted by lice" , "Disease causing high fever and skin rash" .)