Young woman with a kind of fever (5)
I believe the answer is:
lassa
'kind of fever' is the definition.
(I've seen this in another clue)
'young woman with a' is the wordplay.
'young woman' becomes 'lass' (informal term for a young woman).
'with' says to put letters next to each other.
'lass'+'a'='LASSA'
(Other definitions for lassa that I've seen before include "sort of fever" , "-- Fever, acute viral disease" , "fever originating in 20 [NIGERIA]" .)