In Judea, the nativity reveals deity (6)
I believe the answer is:
athena
'deity' is the definition.
(I know that Athena is a Greek deity)
'in judea the nativity' is the wordplay.
'in' says the answer is hidden in the clue.
'ATHENA' is hidden within 'judea the nativity'.
'reveals' acts as a link.
(Other definitions for athena that I've seen before include "wise but fierce goddess" , "One-time goddess" , "Greek goddess of wisdom etc." , "Greek goddess of a capital city" .)