Partially immune, asymptomatic and nervous (6)
I believe the answer is:
uneasy
'nervous' is the definition.
(synonyms)
'partially immune asymptomatic and' is the wordplay.
'partially' indicates the answer is hidden within the clue.
'UNEASY' is hidden within 'immune asymptomatic and'.
(Other definitions for uneasy that I've seen before include "This is neither settled" , "Anxious, nervous" , "as a crowned head, proverbially" , "Jumpy" , "Thus lies the head that wears the crown" .)