Old maid in Nazi administration (6)
I believe the answer is:
zinnia
'old maid' is the definition.
(synonyms)
'in nazi administration' is the wordplay.
'in nazi' can be anagrammed to 'ZINNIA'.
However, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for zinnia that I've seen before include "Garden flower" , "Showy flower (last in any index?)" , "Flowering plant" , "bloomers" , "Showy plant of the daisy family" .)